[syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    944aacb68baf Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f88dfa580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16259d9a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1971a9dd2936/disk-944aacb6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cf50ec150c97/vmlinux-944aacb6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/eee3d7722c03/bzImage-944aacb6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2cecf0e829ae2219d419@syzkaller.appspotmail.com

------------[ cut here ]------------
wlan1: Failed check-sdata-in-driver check, flags: 0x0
WARNING: net/mac80211/driver-ops.c:255 at drv_get_tsf+0x187/0x6f0 net/mac80211/driver-ops.c:255, CPU#0: kworker/u8:11/3538
Modules linked in:
CPU: 0 UID: 0 PID: 3538 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:drv_get_tsf+0x18d/0x6f0 net/mac80211/driver-ops.c:255
Code: 0a 00 00 4d 85 e4 0f 84 95 04 00 00 e8 8c 9a dc f6 49 81 c4 20 01 00 00 e8 80 9a dc f6 48 8d 3d 49 e9 b6 05 44 89 f2 4c 89 e6 <67> 48 0f b9 3a e8 69 9a dc f6 4c 89 ea 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc9000c49fb08 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88805c0c4d80 RCX: ffffffff8ae1c32f
RDX: 0000000000000000 RSI: ffff88805c0c4120 RDI: ffffffff9098acd0
RBP: ffff888031cc8e80 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88803190c830 R12: ffff88805c0c4120
R13: ffff88805c0c57b8 R14: 0000000000000000 R15: ffff888031cc86d0
FS:  0000000000000000(0000) GS:ffff8881248f9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f239b3156c0 CR3: 0000000075ed0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ieee80211_if_fmt_tsf+0x42/0x70 net/mac80211/debugfs_netdev.c:659
 wiphy_locked_debugfs_read_work+0xe6/0x1c0 net/wireless/debugfs.c:168
 cfg80211_wiphy_work+0x3fb/0x560 net/wireless/core.c:438
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	00 00                	add    %al,(%rax)
   2:	4d 85 e4             	test   %r12,%r12
   5:	0f 84 95 04 00 00    	je     0x4a0
   b:	e8 8c 9a dc f6       	call   0xf6dc9a9c
  10:	49 81 c4 20 01 00 00 	add    $0x120,%r12
  17:	e8 80 9a dc f6       	call   0xf6dc9a9c
  1c:	48 8d 3d 49 e9 b6 05 	lea    0x5b6e949(%rip),%rdi        # 0x5b6e96c
  23:	44 89 f2             	mov    %r14d,%edx
  26:	4c 89 e6             	mov    %r12,%rsi
* 29:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2e:	e8 69 9a dc f6       	call   0xf6dc9a9c
  33:	4c 89 ea             	mov    %r13,%rdx
  36:	48                   	rex.W
  37:	b8 00 00 00 00       	mov    $0x0,%eax
  3c:	00 fc                	add    %bh,%ah
  3e:	ff                   	.byte 0xff


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

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Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

commit 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 (HEAD -> master)
Author: Arnav Kapoor <kapoorarnav43@gmail.com>
Date:   Mon Jan 19 03:03:18 2026 +0530

    mac80211: Fix WARNING in drv_get_tsf debugfs access
    
    The debugfs tsf read function was calling drv_get_tsf() even when the
    interface was not registered with the driver, causing a WARN_ON to be
    triggered. This is inappropriate for debugfs access.
    
    Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
    read function and returning -1ULL directly when the interface is not
    in the driver, avoiding the warning.
    
    Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
    Signed-off-by: Arnav Kapoor <kapoorarnav43@gmail.com>

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }

On Monday, 19 January 2026 at 02:56:22 UTC+5:30 syzbot wrote:

Hello, 

syzbot found the following issue on: 

HEAD commit: 944aacb68baf Merge tag 'scsi-fixes' of git://git.kernel.or.. 
git tree: upstream 
console output: https://syzkaller.appspot.com/x/log.txt?x=15f88dfa580000 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16259d9a580000 

Downloadable assets: 
disk image: 
https://storage.googleapis.com/syzbot-assets/1971a9dd2936/disk-944aacb6.raw.xz 
vmlinux: 
https://storage.googleapis.com/syzbot-assets/cf50ec150c97/vmlinux-944aacb6.xz 
kernel image: 
https://storage.googleapis.com/syzbot-assets/eee3d7722c03/bzImage-944aacb6.xz 

IMPORTANT: if you fix the issue, please add the following tag to the 
commit: 
Reported-by: syzbot+2cecf0...@syzkaller.appspotmail.com 

------------[ cut here ]------------ 
wlan1: Failed check-sdata-in-driver check, flags: 0x0 
WARNING: net/mac80211/driver-ops.c:255 at drv_get_tsf+0x187/0x6f0 
net/mac80211/driver-ops.c:255, CPU#0: kworker/u8:11/3538 
Modules linked in: 
CPU: 0 UID: 0 PID: 3538 Comm: kworker/u8:11 Not tainted syzkaller #0 
PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS 
Google 10/25/2025 
Workqueue: events_unbound cfg80211_wiphy_work 
RIP: 0010:drv_get_tsf+0x18d/0x6f0 net/mac80211/driver-ops.c:255 
Code: 0a 00 00 4d 85 e4 0f 84 95 04 00 00 e8 8c 9a dc f6 49 81 c4 20 01 00 
00 e8 80 9a dc f6 48 8d 3d 49 e9 b6 05 44 89 f2 4c 89 e6 <67> 48 0f b9 3a 
e8 69 9a dc f6 4c 89 ea 48 b8 00 00 00 00 00 fc ff 
RSP: 0018:ffffc9000c49fb08 EFLAGS: 00010293 
RAX: 0000000000000000 RBX: ffff88805c0c4d80 RCX: ffffffff8ae1c32f 
RDX: 0000000000000000 RSI: ffff88805c0c4120 RDI: ffffffff9098acd0 
RBP: ffff888031cc8e80 R08: 0000000000000005 R09: 0000000000000000 
R10: 0000000000000000 R11: ffff88803190c830 R12: ffff88805c0c4120 
R13: ffff88805c0c57b8 R14: 0000000000000000 R15: ffff888031cc86d0 
FS: 0000000000000000(0000) GS:ffff8881248f9000(0000) knlGS:0000000000000000 
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 
CR2: 00007f239b3156c0 CR3: 0000000075ed0000 CR4: 00000000003526f0 
Call Trace: 
<TASK> 
ieee80211_if_fmt_tsf+0x42/0x70 net/mac80211/debugfs_netdev.c:659 
wiphy_locked_debugfs_read_work+0xe6/0x1c0 net/wireless/debugfs.c:168 
cfg80211_wiphy_work+0x3fb/0x560 net/wireless/core.c:438 
process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 
process_scheduled_works kernel/workqueue.c:3340 [inline] 
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 
kthread+0x3c5/0x780 kernel/kthread.c:463 
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 
</TASK> 
---------------- 
Code disassembly (best guess), 1 bytes skipped: 
0: 00 00 add %al,(%rax) 
2: 4d 85 e4 test %r12,%r12 
5: 0f 84 95 04 00 00 je 0x4a0 
b: e8 8c 9a dc f6 call 0xf6dc9a9c 
10: 49 81 c4 20 01 00 00 add $0x120,%r12 
17: e8 80 9a dc f6 call 0xf6dc9a9c 
1c: 48 8d 3d 49 e9 b6 05 lea 0x5b6e949(%rip),%rdi # 0x5b6e96c 
23: 44 89 f2 mov %r14d,%edx 
26: 4c 89 e6 mov %r12,%rsi 
* 29: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 
2e: e8 69 9a dc f6 call 0xf6dc9a9c 
33: 4c 89 ea mov %r13,%rdx 
36: 48 rex.W 
37: b8 00 00 00 00 mov $0x0,%eax 
3c: 00 fc add %bh,%ah 
3e: ff .byte 0xff 


--- 
This report is generated by a bot. It may contain errors. 
See https://goo.gl/tpsmEJ for more information about syzbot. 
syzbot engineers can be reached at syzk...@googlegroups.com. 

syzbot will keep track of this issue. See: 
https://goo.gl/tpsmEJ#status for how to communicate with syzbot. 

If the report is already addressed, let syzbot know by replying with: 
#syz fix: exact-commit-title 

If you want syzbot to run the reproducer, reply with: 
#syz test: git://repo/address.git branch-or-commit-hash 
If you attach or paste a git patch, syzbot will apply it before testing. 

If you want to overwrite report's subsystems, reply with: 
#syz set subsystems: new-subsystem 
(See the list of subsystem names on the web dashboard) 

If the report is a duplicate of another one, reply with: 
#syz dup: exact-subject-of-another-report 

If you want to undo deduplication, reply with: 
#syz undup 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

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Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 03:18:05 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=14da53fa580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 03:39:05 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=127ba852580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 04:05:04 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=13ff6b9a580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 04:18:05 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=13d7a852580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

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Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 04:32:04 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=1217db9a580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched 
in
 gc_worker

Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.

Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
 net/netfilter/nf_conntrack_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c 
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
                        break;
                }
 
+                int entry_count = 0;
                hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
                        struct nf_conntrack_net *cnet;
                        struct net *net;
                        long expires;
 
                        tmp = nf_ct_tuplehash_to_ctrack(h);
+                        entry_count++;
 
+                        if (entry_count > 100) break;
+                        cond_resched();
                        if (expired_count > GC_SCAN_EXPIRED_MAX) {
                                rcu_read_unlock();
 
-- 
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched 
in
 gc_worker

Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.

Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
 net/netfilter/nf_conntrack_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c 
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
                        break;
                }
 
+                int entry_count = 0;
                hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
                        struct nf_conntrack_net *cnet;
                        struct net *net;
                        long expires;
 
                        tmp = nf_ct_tuplehash_to_ctrack(h);
+                        entry_count++;
 
+                        if (entry_count > 100) break;
+                        cond_resched();
                        if (expired_count > GC_SCAN_EXPIRED_MAX) {
                                rcu_read_unlock();
 
-- 
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched 
in
 gc_worker

Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.

Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
 net/netfilter/nf_conntrack_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c 
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
                        break;
                }
 
+                int entry_count = 0;
                hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
                        struct nf_conntrack_net *cnet;
                        struct net *net;
                        long expires;
 
                        tmp = nf_ct_tuplehash_to_ctrack(h);
+                        entry_count++;
 
+                        if (entry_count > 100) break;
+                        cond_resched();
                        if (expired_count > GC_SCAN_EXPIRED_MAX) {
                                rcu_read_unlock();
 
-- 
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched 
in
 gc_worker

Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.

Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
 net/netfilter/nf_conntrack_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c 
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
                        break;
                }
 
+                int entry_count = 0;
                hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
                        struct nf_conntrack_net *cnet;
                        struct net *net;
                        long expires;
 
                        tmp = nf_ct_tuplehash_to_ctrack(h);
+                        entry_count++;
 
+                        if (entry_count > 100) break;
+                        cond_resched();
                        if (expired_count > GC_SCAN_EXPIRED_MAX) {
                                rcu_read_unlock();
 
-- 
2.43.0From e0dd0088f4b871d8c44d5b9ba17dd9eba1f770a0 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 04:48:19 +0530
Subject: [PATCH] netfilter: nf_conntrack: add entry limit and cond_resched 
in
 gc_worker

Further limit the gc_worker to process at most 100 entries per bucket
and add cond_resched() at the start of each entry processing to ensure
frequent yielding and prevent RCU stalls.

Reported-by: syzbot+8bb3e2bee8a429cc76dd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8bb3e2bee8a429cc76dd
---
 net/netfilter/nf_conntrack_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c 
b/net/netfilter/nf_conntrack_core.c
index 8a2cdd172..ff901a2b4 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1552,13 +1552,17 @@ static void gc_worker(struct work_struct *work)
                        break;
                }
 
+                int entry_count = 0;
                hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
                        struct nf_conntrack_net *cnet;
                        struct net *net;
                        long expires;
 
                        tmp = nf_ct_tuplehash_to_ctrack(h);
+                        entry_count++;
 
+                        if (entry_count > 100) break;
+                        cond_resched();
                        if (expired_count > GC_SCAN_EXPIRED_MAX) {
                                rcu_read_unlock();
 
-- 
2.43.0

On Monday, 19 January 2026 at 04:50:05 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=100fdb9a580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 04:58:06 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

failed to apply patch after dry run: 
patching file net/netfilter/nf_conntrack_core.c 
Hunk #1 succeeded at 1551 (offset -1 lines). 
patching file net/netfilter/nf_conntrack_core.c 
Hunk #1 FAILED at 1552. 
1 out of 1 hunk FAILED -- saving rejects to file 
net/netfilter/nf_conntrack_core.c.rej 
patching file net/netfilter/nf_conntrack_core.c 
Hunk #1 FAILED at 1552. 
1 out of 1 hunk FAILED -- saving rejects to file 
net/netfilter/nf_conntrack_core.c.rej 
patching file net/netfilter/nf_conntrack_core.c 
Hunk #1 FAILED at 1552. 
1 out of 1 hunk FAILED -- saving rejects to file 
net/netfilter/nf_conntrack_core.c.rej 
patching file net/netfilter/nf_conntrack_core.c 
Hunk #1 FAILED at 1552. 
1 out of 1 hunk FAILED -- saving rejects to file 
net/netfilter/nf_conntrack_core.c.rej 



Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: 
patch: https://syzkaller.appspot.com/x/patch.diff?x=112153fa580000 

Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 05:09:05 UTC+5:30 syzbot wrote:

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=17a44b9a580000 

Forwarded: Private message regarding: Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: Private message regarding: Forwarded: Private message regarding: [syzbot] [wireless?] WARNING in drv_get_tsf (2)
Author: kapoorarnav43@gmail.com

#syz test

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001
From: Arnav Kapoor <kapoorarnav43@gmail.com>
Date: Mon, 19 Jan 2026 03:03:18 +0530
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access

The debugfs tsf read function was calling drv_get_tsf() even when the
interface was not registered with the driver, causing a WARN_ON to be
triggered. This is inappropriate for debugfs access.

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs
read function and returning -1ULL directly when the interface is not
in the driver, avoiding the warning.

Reported-by: syzbot+15f88dfa580000@syzkaller.appspotmail.com
Signed-off-by: Arnav Rawat <arnavrawat2000@gmail.com>
---
 net/mac80211/debugfs_netdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 30a5a978a..669e7c519 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf(
        struct ieee80211_local *local = sdata->local;
        u64 tsf;
 
-       tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata);
+       if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
+               tsf = -1ULL;
+       else
+               tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata);
 
        return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf);
 }
-- 
2.43.0

On Monday, 19 January 2026 at 05:21:22 UTC+5:30 syzbot wrote:

For archival purposes, forwarding an incoming command email to 
linux-...@vger.kernel.org, syzkall...@googlegroups.com. 

*** 

Subject: Private message regarding: [syzbot] [wireless?] WARNING in 
drv_get_tsf (2) 
Author: kapoor...@gmail.com 

#syz test 

From 0cd0a5cff75a12d3cf1fa0675950ef0dcc647799 Mon Sep 17 00:00:00 2001 
From: Arnav Kapoor <kapoor...@gmail.com> 
Date: Mon, 19 Jan 2026 03:03:18 +0530 
Subject: [PATCH] mac80211: Fix WARNING in drv_get_tsf debugfs access 

The debugfs tsf read function was calling drv_get_tsf() even when the 
interface was not registered with the driver, causing a WARN_ON to be 
triggered. This is inappropriate for debugfs access. 

Fix this by checking the IEEE80211_SDATA_IN_DRIVER flag in the debugfs 
read function and returning -1ULL directly when the interface is not 
in the driver, avoiding the warning. 

Reported-by: syzbot+15f...@syzkaller.appspotmail.com 
Signed-off-by: Arnav Rawat <arnavra...@gmail.com> 
--- 
net/mac80211/debugfs_netdev.c | 5 ++++- 
1 file changed, 4 insertions(+), 1 deletion(-) 

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c 
index 30a5a978a..669e7c519 100644 
--- a/net/mac80211/debugfs_netdev.c 
+++ b/net/mac80211/debugfs_netdev.c 
@@ -656,7 +656,10 @@ static ssize_t ieee80211_if_fmt_tsf( 
struct ieee80211_local *local = sdata->local; 
u64 tsf; 

- tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data *)sdata); 
+ if (!(sdata->flags & IEEE80211_SDATA_IN_DRIVER)) 
+ tsf = -1ULL; 
+ else 
+ tsf = drv_get_tsf(local, (struct ieee80211_sub_if_data 
*)sdata); 

return scnprintf(buf, buflen, "0x%016llx\n", (unsigned long long) 
tsf); 
} 
-- 
2.43.0 

On Monday, 19 January 2026 at 05:09:05 UTC+5:30 syzbot wrote: 

Hello, 

syzbot tried to test the proposed patch but the build/boot failed: 

net/mac80211/debugfs_netdev.c:662:70: error: expected ')' before 'return' 
net/mac80211/debugfs_netdev.c:665:1: error: expected expression before '}' 
token 
net/mac80211/debugfs_netdev.c:664:80: error: expected ';' before '}' token 
net/mac80211/debugfs_netdev.c:665:1: error: no return statement in function 
returning non-void [-Werror=return-type] 


Tested on: 

commit: e84d9601 Merge tag 'for-6.19-rc5-tag' of git://git.ker.. 
git tree: upstream 
kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be 
dashboard link: https://syzkaller.appspot.com/bug?extid=2cecf0e829ae2219d419 
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for 
Debian) 2.40 
patch: https://syzkaller.appspot.com/x/patch.diff?x=17a44b9a580000