general protection fault in fsg_common_set_num_buffers

Status: upstream: reported C repro on 2026/09/25 01:15
Reported-by: syzbot+f50543928799ebe66212@syzkaller.appspotmail.com
First crash: 12d, last: 12d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 general protection fault in fsg_common_set_num_buffers 2 syz, C 6 5d18h 29d 0/2 upstream: reported C repro on 2026/09/08 13:05
upstream general protection fault in fsg_common_set_num_buffers prio:low usb 10 syz, C 19 26d 51d 27/29 upstream: reported C repro on 2026/08/17 07:39
android-6-12 general protection fault in fsg_common_set_num_buffers 2 syz, C 6 16d 29d 0/1 premoderation: reported C repro on 2026/09/08 12:28
linux-6.1 BUG: unable to handle kernel paging request in fsg_common_set_num_buffers origin:lts-only 8 syz, C 7 23d 29d 0/3 upstream: reported C repro on 2026/09/08 12:35

Sample crash report:
LUN: removable file: (no medium)
general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 PID: 297 Comm: syz-executor110 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:fsg_common_set_num_buffers+0x65/0x2b0 drivers/usb/gadget/function/f_mass_storage.c:2649
Code: 89 c6 49 bd 00 00 00 00 00 fc ff df bf 00 40 00 00 be c0 0c 00 00 ba 02 00 00 00 e8 25 cb 81 fe 48 89 c3 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 6c f4 8e fe 49 89 1e 48 85 db 0f
RSP: 0018:ffffc90000b07b28 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff88811fa44000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8310419b RDI: ffffed1023f49000
RBP: ffffc90000b07b70 R08: 0000000000004000 R09: ffffed1023f49000
R10: dffffc0000000000 R11: fffff940008fd233 R12: ffff88810ae1d000
R13: dffffc0000000000 R14: 0000000000000010 R15: 0000000000000000
FS:  00005555646483c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1979aee008 CR3: 0000000121d14000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 fsg_opts_num_buffers_store+0x138/0x1c0 drivers/usb/gadget/function/f_mass_storage.c:3329
 flush_write_buffer fs/configfs/file.c:251 [inline]
 configfs_write_file+0x320/0x3d0 fs/configfs/file.c:283
 vfs_write+0x344/0xd70 fs/read_write.c:603
 ksys_write+0x14a/0x260 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f1979a51ef9
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:00007ffed86a2138 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000300 RCX: 00007f1979a51ef9
RDX: 0000000000000012 RSI: 0000200000000300 RDI: 0000000000000003
RBP: 6769666e6f632f2e R08: 000000000000000f R09: 00007ffed86a2278
R10: 0000000000000001 R11: 0000000000000246 R12: 00007ffed86a2268
R13: 0000000000000002 R14: 0000200000000008 R15: 0000000000000002
Modules linked in:
---[ end trace e30eb742759e0c0b ]---
RIP: 0010:fsg_common_set_num_buffers+0x65/0x2b0 drivers/usb/gadget/function/f_mass_storage.c:2649
Code: 89 c6 49 bd 00 00 00 00 00 fc ff df bf 00 40 00 00 be c0 0c 00 00 ba 02 00 00 00 e8 25 cb 81 fe 48 89 c3 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 6c f4 8e fe 49 89 1e 48 85 db 0f
RSP: 0018:ffffc90000b07b28 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff88811fa44000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8310419b RDI: ffffed1023f49000
RBP: ffffc90000b07b70 R08: 0000000000004000 R09: ffffed1023f49000
R10: dffffc0000000000 R11: fffff940008fd233 R12: ffff88810ae1d000
R13: dffffc0000000000 R14: 0000000000000010 R15: 0000000000000000
FS:  00005555646483c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1979aee008 CR3: 0000000121d14000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	89 c6                	mov    %eax,%esi
   2:	49 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%r13
   9:	fc ff df
   c:	bf 00 40 00 00       	mov    $0x4000,%edi
  11:	be c0 0c 00 00       	mov    $0xcc0,%esi
  16:	ba 02 00 00 00       	mov    $0x2,%edx
  1b:	e8 25 cb 81 fe       	call   0xfe81cb45
  20:	48 89 c3             	mov    %rax,%rbx
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 6c f4 8e fe       	call   0xfe8ef4a5
  39:	49 89 1e             	mov    %rbx,(%r14)
  3c:	48 85 db             	test   %rbx,%rbx
  3f:	0f                   	.byte 0xf

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/25 02:04 android13-5.10-lts 452567d1985b 3c3cdf19 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in fsg_common_set_num_buffers
2026/09/25 01:43 android13-5.10-lts 452567d1985b 3c3cdf19 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in fsg_common_set_num_buffers
2026/09/25 01:14 android13-5.10-lts 452567d1985b 3c3cdf19 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in fsg_common_set_num_buffers
* Struck through repros no longer work on HEAD.