Re: [syzbot] [kernel?] WARNING in firmware_fallback_sysfs (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    bc35965f6940 Merge tag 'mm-hotfixes-stable-2026-09-03-17-4..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=123d08f9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f
dashboard link: https://syzkaller.appspot.com/bug?extid=8f06445357a052a92657
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=125c6125580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8f06445357a052a92657@xxxxxxxxxxxxxxxxxxxxxxxxx

usb 7-1: Falling back to sysfs fallback for: v4l-pvrusb2-160xxx-01.fw
------------[ cut here ]------------
ret
WARNING: drivers/base/firmware_loader/fallback.c:158 at fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:158 [inline], CPU#0: pvrusb2-context/2510
WARNING: drivers/base/firmware_loader/fallback.c:158 at firmware_fallback_sysfs+0x6ef/0xc60 drivers/base/firmware_loader/fallback.c:248, CPU#0: pvrusb2-context/2510
Modules linked in:
CPU: 0 UID: 0 PID: 2510 Comm: pvrusb2-context 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:fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:158 [inline]
RIP: 0010:firmware_fallback_sysfs+0x6ef/0xc60 drivers/base/firmware_loader/fallback.c:248
Code: ff ff e9 2f 42 d0 fa e8 af ab 9b fb e8 6a 31 5f fb 31 ff 89 c3 89 c6 e8 0f a6 9b fb 85 db 0f 84 f5 fa ff ff e8 92 ab 9b fb 90 <0f> 0b 90 48 8b 3c 24 4c 89 e2 48 c7 c6 20 f2 93 8c e8 6b 11 d0 fa
RSP: 0018:ffffc90007d1f8d0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000fffffff5 RCX: 0000000000000000
RDX: ffff88802e7e2580 RSI: ffffffff8670447e RDI: ffff88802e7e2580
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000fffffff5 R11: 000000000000761b R12: ffffffff8cff0200
R13: ffff888027cff200 R14: 0000000000001770 R15: ffff888027cff210
FS:  0000000000000000(0000) GS:ffff8880d5b60000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f735b1f0980 CR3: 0000000035e42000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 _request_firmware+0xfd7/0x13c0 drivers/base/firmware_loader/main.c:898
 request_firmware+0x35/0x50 drivers/base/firmware_loader/main.c:948
 pvr2_locate_firmware+0x8f/0x330 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:1359
 pvr2_upload_firmware1+0x1ca/0x920 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:1426
 pvr2_hdw_setup_low drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2107 [inline]
 pvr2_hdw_setup drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2261 [inline]
 pvr2_hdw_initialize+0x3e6/0x3710 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2338
 pvr2_context_check drivers/media/usb/pvrusb2/pvrusb2-context.c:111 [inline]
 pvr2_context_thread_func+0x253/0x920 drivers/media/usb/pvrusb2/pvrusb2-context.c:158
 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>


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