* [syzbot] [usb?] general protection fault in fsg_common_set_num_buffers
@ 2026-08-17 7:39 syzbot
2026-08-17 8:07 ` syzbot
0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2026-08-17 7:39 UTC (permalink / raw)
To: gregkh, linux-kernel, linux-usb, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: dcb68831eac7 Merge tag 'block-7.2-20260815' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13dbda79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=791be35f1fbcc85d06d7
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/616b82a1afb9/disk-dcb68831.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b1958ef02ef/vmlinux-dcb68831.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8138e3edc5b6/bzImage-dcb68831.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com
Mass Storage Function, version: 2009/09/11
LUN: removable file: (no medium)
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 UID: 0 PID: 7793 Comm: syz.6.613 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:fsg_common_set_num_buffers+0xad/0x340 drivers/usb/gadget/function/f_mass_storage.c:2763
Code: 42 80 3c 30 00 0f 85 52 02 00 00 48 89 6d e0 e8 99 48 2c fa be c0 0c 00 00 bf 00 40 00 00 e8 ca 6c 90 fa 48 89 ea 48 c1 ea 03 <42> 80 3c 32 00 0f 85 04 02 00 00 48 89 45 00 48 85 c0 75 95 e8 6a
RSP: 0018:ffffc90004637bc0 EFLAGS: 00010202
RAX: ffff88805b230000 RBX: 0000000000000000 RCX: 0000000000004000
RDX: 0000000000000002 RSI: ffffffff8c600300 RDI: ffffffff8e674928
RBP: 0000000000000010 R08: 0000000000000cc0 R09: 00000000ffffffff
R10: ffffed100b646800 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000010 R14: dffffc0000000000 R15: ffff88807824c000
FS: 00007fe3849546c0(0000) GS:ffff888123cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c40497d CR3: 000000005b094000 CR4: 00000000003526f0
Call Trace:
<TASK>
fsg_opts_num_buffers_store+0x168/0x1b0 drivers/usb/gadget/function/f_mass_storage.c:3452
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe38399e0d9
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:00007fe384954028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fe383c25fa0 RCX: 00007fe38399e0d9
RDX: 0000000000000002 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007fe383a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe383c26038 R14: 00007fe383c25fa0 R15: 00007ffcf60b29f8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fsg_common_set_num_buffers+0xad/0x340 drivers/usb/gadget/function/f_mass_storage.c:2763
Code: 42 80 3c 30 00 0f 85 52 02 00 00 48 89 6d e0 e8 99 48 2c fa be c0 0c 00 00 bf 00 40 00 00 e8 ca 6c 90 fa 48 89 ea 48 c1 ea 03 <42> 80 3c 32 00 0f 85 04 02 00 00 48 89 45 00 48 85 c0 75 95 e8 6a
RSP: 0018:ffffc90004637bc0 EFLAGS: 00010202
RAX: ffff88805b230000 RBX: 0000000000000000 RCX: 0000000000004000
RDX: 0000000000000002 RSI: ffffffff8c600300 RDI: ffffffff8e674928
RBP: 0000000000000010 R08: 0000000000000cc0 R09: 00000000ffffffff
R10: ffffed100b646800 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000010 R14: dffffc0000000000 R15: ffff88807824c000
FS: 00007fe3849546c0(0000) GS:ffff888123cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d6ba9dece8 CR3: 000000005b094000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1)
5: 0f 85 52 02 00 00 jne 0x25d
b: 48 89 6d e0 mov %rbp,-0x20(%rbp)
f: e8 99 48 2c fa call 0xfa2c48ad
14: be c0 0c 00 00 mov $0xcc0,%esi
19: bf 00 40 00 00 mov $0x4000,%edi
1e: e8 ca 6c 90 fa call 0xfa906ced
23: 48 89 ea mov %rbp,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 42 80 3c 32 00 cmpb $0x0,(%rdx,%r14,1) <-- trapping instruction
2f: 0f 85 04 02 00 00 jne 0x239
35: 48 89 45 00 mov %rax,0x0(%rbp)
39: 48 85 c0 test %rax,%rax
3c: 75 95 jne 0xffffffd3
3e: e8 .byte 0xe8
3f: 6a .byte 0x6a
---
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 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
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [syzbot] [usb?] general protection fault in fsg_common_set_num_buffers
2026-08-17 7:39 [syzbot] [usb?] general protection fault in fsg_common_set_num_buffers syzbot
@ 2026-08-17 8:07 ` syzbot
0 siblings, 0 replies; 2+ messages in thread
From: syzbot @ 2026-08-17 8:07 UTC (permalink / raw)
To: gregkh, linux-kernel, linux-usb, syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: dcb68831eac7 Merge tag 'block-7.2-20260815' of git://git.k..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12aad6c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=791be35f1fbcc85d06d7
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=1033fa79580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=105cd949580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/616b82a1afb9/disk-dcb68831.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b1958ef02ef/vmlinux-dcb68831.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8138e3edc5b6/bzImage-dcb68831.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 UID: 0 PID: 5606 Comm: syz-executor407 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:fsg_common_set_num_buffers+0xad/0x340 drivers/usb/gadget/function/f_mass_storage.c:2763
Code: 42 80 3c 30 00 0f 85 52 02 00 00 48 89 6d e0 e8 99 48 2c fa be c0 0c 00 00 bf 00 40 00 00 e8 ca 6c 90 fa 48 89 ea 48 c1 ea 03 <42> 80 3c 32 00 0f 85 04 02 00 00 48 89 45 00 48 85 c0 75 95 e8 6a
RSP: 0018:ffffc9000333fbc0 EFLAGS: 00010202
RAX: ffff88807ec24000 RBX: 0000000000000000 RCX: 0000000000004000
RDX: 0000000000000002 RSI: ffffffff8c600300 RDI: ffffffff8e674928
RBP: 0000000000000010 R08: 0000000000000cc0 R09: 00000000ffffffff
R10: ffffed100fd85000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000010 R14: dffffc0000000000 R15: ffff88807c0b4000
FS: 000055556964e400(0000) GS:ffff888123cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056020ff0f000 CR3: 00000000772e6000 CR4: 00000000003526f0
Call Trace:
<TASK>
fsg_opts_num_buffers_store+0x168/0x1b0 drivers/usb/gadget/function/f_mass_storage.c:3452
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb82a557cb9
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc1e17d488 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007fb82a557cb9
RDX: 0000000000000002 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 6769666e6f632f2e R08: 0000000000000000 R09: 00007ffc1e17d5c8
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc1e17d5b8
R13: 0000000000000002 R14: 0000200000000008 R15: 0000000000000002
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fsg_common_set_num_buffers+0xad/0x340 drivers/usb/gadget/function/f_mass_storage.c:2763
Code: 42 80 3c 30 00 0f 85 52 02 00 00 48 89 6d e0 e8 99 48 2c fa be c0 0c 00 00 bf 00 40 00 00 e8 ca 6c 90 fa 48 89 ea 48 c1 ea 03 <42> 80 3c 32 00 0f 85 04 02 00 00 48 89 45 00 48 85 c0 75 95 e8 6a
RSP: 0018:ffffc9000333fbc0 EFLAGS: 00010202
RAX: ffff88807ec24000 RBX: 0000000000000000 RCX: 0000000000004000
RDX: 0000000000000002 RSI: ffffffff8c600300 RDI: ffffffff8e674928
RBP: 0000000000000010 R08: 0000000000000cc0 R09: 00000000ffffffff
R10: ffffed100fd85000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000010 R14: dffffc0000000000 R15: ffff88807c0b4000
FS: 000055556964e400(0000) GS:ffff888123cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056020ff0f000 CR3: 00000000772e6000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1)
5: 0f 85 52 02 00 00 jne 0x25d
b: 48 89 6d e0 mov %rbp,-0x20(%rbp)
f: e8 99 48 2c fa call 0xfa2c48ad
14: be c0 0c 00 00 mov $0xcc0,%esi
19: bf 00 40 00 00 mov $0x4000,%edi
1e: e8 ca 6c 90 fa call 0xfa906ced
23: 48 89 ea mov %rbp,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 42 80 3c 32 00 cmpb $0x0,(%rdx,%r14,1) <-- trapping instruction
2f: 0f 85 04 02 00 00 jne 0x239
35: 48 89 45 00 mov %rax,0x0(%rbp)
39: 48 85 c0 test %rax,%rax
3c: 75 95 jne 0xffffffd3
3e: e8 .byte 0xe8
3f: 6a .byte 0x6a
---
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.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-08-17 7:39 [syzbot] [usb?] general protection fault in fsg_common_set_num_buffers syzbot
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