[syzbot] [net?] [afs?] kernel BUG in rxrpc_purge_client_connections

[syzbot] [net?] [afs?] kernel BUG in rxrpc_purge_client_connections

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f0100363d8c3 Merge tag 'xfs-fixes-7.3-rc5' of gitolite.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11f20c5e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7d012d9c67977ee4
dashboard link: https://syzkaller.appspot.com/bug?extid=e2f5927fc701355ef101
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15f20c5e580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11ae34c9580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f0100363.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/57240753f5ee/vmlinux-f0100363.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2930b9a97546/bzImage-f0100363.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e2f5927fc701355ef101@syzkaller.appspotmail.com

rxrpc: AF_RXRPC: Leaked client conn ffff888055bb9000 {1}
------------[ cut here ]------------
kernel BUG at net/rxrpc/conn_client.c:64!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5919 Comm: krxrpcio/4660 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:rxrpc_destroy_client_conn_ids net/rxrpc/conn_client.c:64 [inline]
RIP: 0010:rxrpc_purge_client_connections+0xc0/0x1a0 net/rxrpc/conn_client.c:145
Code: 2b 31 db 48 8d 6c 24 28 e8 ed 4b 15 f7 48 89 ee 4c 89 ef 89 5c 24 28 e8 1e 7f d0 00 48 89 c3 48 85 c0 75 73 e8 d1 4b 15 f7 90 <0f> 0b e8 c9 4b 15 f7 31 f6 4c 89 ef e8 4f 5f d5 00 31 ff 89 c3 89
RSP: 0018:ffffc900038e7a80 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888024d3cb00 RSI: ffffffff8af6d6bf RDI: ffff888024d3cb00
RBP: ffffc900038e7aa8 R08: 0000000000000007 R09: 000000007fffffff
R10: 000000002bb346e4 R11: 0000000000000001 R12: ffff888055bb9038
R13: ffff888054eb7270 R14: ffff888054eb7038 R15: ffff888038d94180
FS:  0000000000000000(0000) GS:ffff8880d5b53000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 000000003566e000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 rxrpc_destroy_local+0x262/0x300 net/rxrpc/local_object.c:451
 rxrpc_io_thread+0x2e1a/0x3820 net/rxrpc/io_thread.c:579
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rxrpc_destroy_client_conn_ids net/rxrpc/conn_client.c:64 [inline]
RIP: 0010:rxrpc_purge_client_connections+0xc0/0x1a0 net/rxrpc/conn_client.c:145
Code: 2b 31 db 48 8d 6c 24 28 e8 ed 4b 15 f7 48 89 ee 4c 89 ef 89 5c 24 28 e8 1e 7f d0 00 48 89 c3 48 85 c0 75 73 e8 d1 4b 15 f7 90 <0f> 0b e8 c9 4b 15 f7 31 f6 4c 89 ef e8 4f 5f d5 00 31 ff 89 c3 89
RSP: 0018:ffffc900038e7a80 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888024d3cb00 RSI: ffffffff8af6d6bf RDI: ffff888024d3cb00
RBP: ffffc900038e7aa8 R08: 0000000000000007 R09: 000000007fffffff
R10: 000000002bb346e4 R11: 0000000000000001 R12: ffff888055bb9038
R13: ffff888054eb7270 R14: ffff888054eb7038 R15: ffff888038d94180
FS:  0000000000000000(0000) GS:ffff8880d5c53000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33024008 CR3: 000000000eb96000 CR4: 0000000000352ef0


---
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

Re: [syzbot] [net?] [afs?] kernel BUG in rxrpc_purge_client_connections

[Edward Adam Davis]

From: Edward Aadm Davis <eadavis@sina.com>

#syz test: upstream f0100363d8c3

diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 48519f0de185..9f13520be249 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -335,6 +335,7 @@ int rxrpc_look_up_bundle(struct rxrpc_call *call, gfp_t gfp)
 /*
  * Allocate a new connection and add it into a bundle.
  */
+static void rxrpc_unbundle_conn(struct rxrpc_connection *conn);
 static bool rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle,
 				     unsigned int slot)
 {
@@ -344,6 +345,7 @@ static bool rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle,
 
 	old = bundle->conns[slot];
 	if (old) {
+		rxrpc_unbundle_conn(old);
 		bundle->conns[slot] = NULL;
 		bundle->conn_ids[slot] = 0;
 		trace_rxrpc_client(old, -1, rxrpc_client_replace);

Re: [syzbot] [net?] [afs?] kernel BUG in rxrpc_purge_client_connections

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+e2f5927fc701355ef101@syzkaller.appspotmail.com
Tested-by: syzbot+e2f5927fc701355ef101@syzkaller.appspotmail.com

Tested on:

commit:         f0100363 Merge tag 'xfs-fixes-7.3-rc5' of gitolite.ker..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=166f0d25580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7d012d9c67977ee4
dashboard link: https://syzkaller.appspot.com/bug?extid=e2f5927fc701355ef101
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13570d25580000

Note: testing is done by a robot and is best-effort only.

[PATCH] rxrpc: add missing unbundle old conn

[Edward Adam Davis]

When adding a new connection to the bundle, the old connection was not
removed from the bundle before being dropped, potentially hitting:

kernel BUG at net/rxrpc/conn_client.c:64!
RIP: 0010:rxrpc_destroy_client_conn_ids net/rxrpc/conn_client.c:64 [inline]
RIP: 0010:rxrpc_purge_client_connections+0xc0/0x1a0 net/rxrpc/conn_client.c:145
Call Trace:
 rxrpc_destroy_local+0x262/0x300 net/rxrpc/local_object.c:451
 rxrpc_io_thread+0x2e1a/0x3820 net/rxrpc/io_thread.c:579

Old connections that cannot be reused need to be unbundled.

Reported-by: syzbot+e2f5927fc701355ef101@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e2f5927fc701355ef101
Tested-by: syzbot+e2f5927fc701355ef101@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@sina.com>
---
 net/rxrpc/conn_client.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 48519f0de185..9f13520be249 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -335,6 +335,7 @@ int rxrpc_look_up_bundle(struct rxrpc_call *call, gfp_t gfp)
 /*
  * Allocate a new connection and add it into a bundle.
  */
+static void rxrpc_unbundle_conn(struct rxrpc_connection *conn);
 static bool rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle,
 				     unsigned int slot)
 {
@@ -344,6 +345,7 @@ static bool rxrpc_add_conn_to_bundle(struct rxrpc_bundle *bundle,
 
 	old = bundle->conns[slot];
 	if (old) {
+		rxrpc_unbundle_conn(old);
 		bundle->conns[slot] = NULL;
 		bundle->conn_ids[slot] = 0;
 		trace_rxrpc_client(old, -1, rxrpc_client_replace);
-- 
2.43.0