[syzbot] [spi?] [usb?] WARNING in spi_register_controller (2)

[syzbot] [spi?] [usb?] WARNING in spi_register_controller (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    c339f4010dea Merge tag 'platform-drivers-x86-v7.4-1' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17d07259580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4a49f7c2815c8df7
dashboard link: https://syzkaller.appspot.com/bug?extid=41172204e7323356ecdb
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1420a1a5580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1271cef1580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-c339f401.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2aba9a3fc60c/vmlinux-c339f401.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a3c085a78213/bzImage-c339f401.xz

AI-generated root cause summary:
In spi_controller_id_alloc() (drivers/spi/spi.c), idr_alloc() can return -ENOMEM
when radix tree memory allocation fails under memory pressure or fault
injection. The function inappropriately invokes WARN(id < 0, "couldn't get idr")
on any failure rather than handling expected runtime allocation errors silently.
In production builds without panic_on_warn, execution continues, locks are
properly released, and the error is cleanly propagated and handled by callers
without causing denial of service or memory corruption.

full analysis:  https://syzkaller.appspot.com/x/ai_root_cause?x=41172204e7323356ecdb

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+41172204e7323356ecdb@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fe4d0225fac R14: 00007fe4d0225fa0 R15: 00007fe4d0225fa0
 </TASK>
------------[ cut here ]------------
couldn't get idr
WARNING: drivers/spi/spi.c:3634 at spi_controller_id_alloc drivers/spi/spi.c:3634 [inline], CPU#0: syz.0.17/5588
WARNING: drivers/spi/spi.c:3634 at spi_register_controller+0x1261/0x1670 drivers/spi/spi.c:3697, CPU#0: syz.0.17/5588
Modules linked in:
CPU: 0 UID: 0 PID: 5588 Comm: syz.0.17 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:spi_controller_id_alloc drivers/spi/spi.c:3634 [inline]
RIP: 0010:spi_register_controller+0x1261/0x1670 drivers/spi/spi.c:3697
Code: 8c e8 33 d5 79 fa e9 1e ff ff ff e8 a9 a6 16 fb 48 8d 3d 72 3f 18 0b 67 48 0f b9 3a eb 11 e8 96 a6 16 fb 48 8d 3d 6f 3f 18 0b <67> 48 0f b9 3a bf e4 ff ff ff 44 89 f6 e8 8d ab 16 fb 41 83 fe e4
RSP: 0018:ffffc90004de7878 EFLAGS: 00010293
RAX: ffffffff86b27e5a RBX: ffff888050e4a000 RCX: ffff888034fc4b00
RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: ffffffff91cabdd0
RBP: 0000000000000000 R08: ffffc90004de7807 R09: 1ffff920009bcf00
R10: dffffc0000000000 R11: fffff520009bcf01 R12: 1ffff1100a1c9408
R13: dffffc0000000000 R14: 00000000fffffff4 R15: ffff888050e4a4d8
FS:  000055558743d500(0000) GS:ffff88808aa10000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbfc3e0ca90 CR3: 0000000040ab8000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 msi2500_probe+0x4c6/0x9e0 drivers/media/usb/msi2500/msi2500.c:1249
 usb_probe_interface+0x751/0xe00 drivers/usb/core/driver.c:399
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:707
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:869
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:899
 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1027
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:503
 __device_attach+0x2bd/0x430 drivers/base/dd.c:1131
 proc_ioctl+0x409/0x660 drivers/usb/core/devio.c:2370
 proc_ioctl_default+0xc4/0x110 drivers/usb/core/devio.c:2405
 usbdev_do_ioctl drivers/usb/core/devio.c:2769 [inline]
 usbdev_ioctl+0x139d/0x21a0 drivers/usb/core/devio.c:2829
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe4cff9f559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc6b706298 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe4d0225fa0 RCX: 00007fe4cff9f559
RDX: 0000200000000900 RSI: 00000000c0105512 RDI: 0000000000000004
RBP: 00007ffc6b706300 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fe4d0225fac R14: 00007fe4d0225fa0 R15: 00007fe4d0225fa0
 </TASK>
----------------
Code disassembly (best guess):
   0:	8c e8                	mov    %gs,%eax
   2:	33 d5                	xor    %ebp,%edx
   4:	79 fa                	jns    0x0
   6:	e9 1e ff ff ff       	jmp    0xffffff29
   b:	e8 a9 a6 16 fb       	call   0xfb16a6b9
  10:	48 8d 3d 72 3f 18 0b 	lea    0xb183f72(%rip),%rdi        # 0xb183f89
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 11                	jmp    0x2f
  1e:	e8 96 a6 16 fb       	call   0xfb16a6b9
  23:	48 8d 3d 6f 3f 18 0b 	lea    0xb183f6f(%rip),%rdi        # 0xb183f99
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	bf e4 ff ff ff       	mov    $0xffffffe4,%edi
  34:	44 89 f6             	mov    %r14d,%esi
  37:	e8 8d ab 16 fb       	call   0xfb16abc9
  3c:	41 83 fe e4          	cmp    $0xffffffe4,%r14d


---
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Forwarded: [PATCH] spi: core: do not WARN on allocation failure in spi_controller_id_alloc

[syzbot]

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

***

Subject: [PATCH] spi: core: do not WARN on allocation failure in spi_controller_id_alloc
Author: gowtham398gs@gmail.com


#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Signed-off-by: Gowtham S Bhushan <gowtham398gs@gmail.com>
---
 drivers/spi/spi.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 40cda0037ea5..319fe204da3a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3631,8 +3631,17 @@ static int spi_controller_id_alloc(struct spi_controller *ctlr, int start, int e
 	mutex_lock(&board_lock);
 	id = idr_alloc(&spi_controller_idr, ctlr, start, end, GFP_KERNEL);
 	mutex_unlock(&board_lock);
-	if (WARN(id < 0, "couldn't get idr"))
+
+	/*
+	 * Modify the error handling path to only trigger a WARN when the failure
+         * is not due to an out-of-memory condition
+	 */
+
+	if (id < 0) {
+		WARN(id != -ENOMEM, "couldn't get idr");
 		return id == -ENOSPC ? -EBUSY : id;
+	}
+
 	ctlr->bus_num = id;
 	return 0;
 }
-- 
2.56.0