* Re: Private message regarding: [syzbot] [pci?] WARNING in pci_scan_single_device (2)
[not found] <ceecf9ca-065f-43f2-9652-ce3f2b79225en@googlegroups.com>
@ 2026-01-21 7:00 ` syzbot
0 siblings, 0 replies; only message in thread
From: syzbot @ 2026-01-21 7:00 UTC (permalink / raw)
To: kapoorarnav43; +Cc: kapoorarnav43, linux-kernel, syzkaller-bugs
> #syz test
>
> From: Arnav Kapoor <kapoorarnav43@gmail.com>
> Date: Tue, 21 Jan 2026 05:30:00 +0530
> Subject: [PATCH] PCI: Replace WARN_ON with proper error handling in
> pci_device_add
>
> The WARN_ON macro in pci_device_add triggers kernel warnings when
> device_add()
> fails due to memory pressure or error injection. This is inappropriate for
> normal error conditions that can occur in fuzzing scenarios.
>
> Replace WARN_ON with proper error handling and logging:
> - Convert firmware device_add failure to error logging
> - Convert kernel device_add failure to error logging and cleanup
> - Properly handle failure cases without triggering spurious warnings
>
> Reported-by: syzbot+87bb32e345aa80c0554b@syzkaller.appspotmail.com
> Signed-off-by: Arnav Kapoor <kapoorarnav43@gmail.com>
> ---
> drivers/pci/probe.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 669e7c519..9238ec951 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2795,16 +2795,26 @@ void pci_device_add(struct pci_dev *dev, struct
> pci_bus *bus)
> ret = pcibios_device_add(dev);
> - WARN_ON(ret < 0);
> + if (ret < 0) {
> + pci_warn(dev, "pcibios_device_add failed\n");
> + }
>
> /* Set up MSI IRQ domain */
> pci_set_msi_domain(dev);
>
> /* Notifier could use PCI capabilities */
> ret = device_add(&dev->dev);
> - WARN_ON(ret < 0);
> + if (ret < 0) {
> + pci_warn(dev, "device_add failed\n");
> + /* Clean up the device from the bus list */
> + down_write(&pci_bus_sem);
> + list_del(&dev->bus_list);
> + up_write(&pci_bus_sem);
> + return;
> + }
>
> /* Establish pdev->tsm for newly added (e.g. new SR-IOV VFs) */
> pci_tsm_init(dev);
>
> pci_npem_create(dev);
>
> pci_doe_sysfs_init(dev);
> }
>
> --
> 2.43.0
>
> On Wednesday, 21 January 2026 at 05:38:30 UTC+5:30 syzbot wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 983d014aafb1 kernel: modules: Add SPDX license identifier ..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10658852580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ae589cd0a6acd9be
> dashboard link: https://syzkaller.appspot.com/bug?extid=87bb32e345aa80c0554b
> compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for
> Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image:
> https://storage.googleapis.com/syzbot-assets/8a294469166c/disk-983d014a.raw.xz
> vmlinux:
> https://storage.googleapis.com/syzbot-assets/f9504a6df5a7/vmlinux-983d014a.xz
> kernel image:
> https://storage.googleapis.com/syzbot-assets/88a1d939d6af/bzImage-983d014a.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the
> commit:
> Reported-by: syzbot+87bb32...@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> WARNING: drivers/pci/probe.c:2800 at pci_device_add+0x105e/0x1490
> drivers/pci/probe.c:2800, CPU#0: syz.5.1730/14510
> Modules linked in:
> CPU: 0 UID: 0 PID: 14510 Comm: syz.5.1730 Tainted: G U L syzkaller #0
> PREEMPT(full)
> Tainted: [U]=USER, [L]=SOFTLOCKUP
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 10/25/2025
> RIP: 0010:pci_device_add+0x105e/0x1490 drivers/pci/probe.c:2800
> Code: e5 04 83 e0 8f 09 e8 88 83 c0 00 00 00 e9 ef f2 ff ff e8 85 7a d6 fc
> 90 0f 0b 90 90 0f 0b 90 e9 ee f4 ff ff e8 73 7a d6 fc 90 <0f> 0b 90 e9 c1
> f7 ff ff e8 65 7a d6 fc 90 0f 0b 90 e9 54 f7 ff ff
> RSP: 0018:ffffc9000bb5f938 EFLAGS: 00010283
> RAX: 000000000003659d RBX: 00000000fffffff4 RCX: ffffc90015bd3000
> RDX: 0000000000080000 RSI: ffffffff84e7e38d RDI: 0000000000000005
> RBP: ffff88801bae0400 R08: 0000000000000005 R09: 0000000000000000
> R10: 00000000fffffff4 R11: ffffffff81000130 R12: ffff888142e87028
> R13: ffff888142e87000 R14: 0000000000000001 R15: ffff888142ea2000
> FS: 00007fa6b528e6c0(0000) GS:ffff8881248f9000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000020000058e000 CR3: 000000007e2d4000 CR4: 00000000003526f0
> Call Trace:
> <TASK>
> pci_scan_single_device drivers/pci/probe.c:2824 [inline]
> pci_scan_single_device+0x252/0x310 drivers/pci/probe.c:2810
> pci_scan_slot+0x1c0/0x760 drivers/pci/probe.c:2907
> pci_scan_child_bus_extend+0x6b/0x7d0 drivers/pci/probe.c:3126
> pci_scan_child_bus drivers/pci/probe.c:3239 [inline]
> pci_rescan_bus+0x18/0x40 drivers/pci/probe.c:3530
> rescan_store+0xfb/0x130 drivers/pci/pci-sysfs.c:472
> bus_attr_store+0x74/0xb0 drivers/base/bus.c:172
> sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142
> kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352
> new_sync_write fs/read_write.c:593 [inline]
> vfs_write+0x7d3/0x11d0 fs/read_write.c:686
> ksys_write+0x12a/0x250 fs/read_write.c:738
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fa6b438f7c9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fa6b528e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007fa6b45e5fa0 RCX: 00007fa6b438f7c9
> RDX: 0000000000000001 RSI: 0000200000000200 RDI: 0000000000000003
> RBP: 00007fa6b4413f91 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fa6b45e6038 R14: 00007fa6b45e5fa0 R15: 00007ffd9a287b48
> </TASK>
>
>
> ---
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>
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Command #1:
This crash does not have a reproducer. I cannot test it.
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