[syzbot] [kernel?] general protection fault in proc_sys_call_handler

syzbot
2025-01-04T01:20:27Z

Hello,

syzbot found the following issue on:

HEAD commit: ccb98ccef0e5 Merge tag 'platform-drivers-x86-v6.13-4' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f1eaf8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=86dd15278dbfe19f
dashboard link: https://syzkaller.appspot.com/bug?extid=2e65930fda17880da336
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=140888b0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d24eb225cff7/disk-ccb98cce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dd81532f8240/vmlinux-ccb98cce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/18b08e4bbf40/bzImage-ccb98cce.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2e65930fda17880da336@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 UID: 0 PID: 5943 Comm: syz-executor Not tainted 6.13.0-rc5-syzkaller-00004-gccb98ccef0e5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:get_uts kernel/utsname_sysctl.c:23 [inline]
RIP: 0010:proc_do_uts_string+0x137/0x4e0 kernel/utsname_sysctl.c:50
Code: 48 c1 ee 03 80 3c 0e 00 0f 85 56 03 00 00 48 8b 92 08 09 00 00 48 b9 00 00 00 00 00 fc ff df 48 8d 7a 08 48 89 fe 48 c1 ee 03 <80> 3c 0e 00 0f 85 12 03 00 00 48 be 00 00 00 00 00 fc ff df 48 2d
RSP: 0018:ffffc900038f7468 EFLAGS: 00010202
RAX: ffffffff90022485 RBX: 1ffff9200071ee92 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000008
RBP: ffffffff8de39fd8 R08: 0000000000000001 R09: fffffbfff1b8e071
R10: ffffffff8dc7038f R11: 0000000000000002 R12: 0000000000000001
R13: ffffc900038f7520 R14: dffffc0000000000 R15: ffffffff8de39fe0
FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0544972008 CR3: 000000000db7e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
proc_sys_call_handler+0x403/0x5d0 fs/proc/proc_sysctl.c:601
__kernel_write_iter+0x318/0xa80 fs/read_write.c:612
__kernel_write+0xf6/0x140 fs/read_write.c:632
do_acct_process+0xcb0/0x14a0 kernel/acct.c:539
acct_pin_kill+0x2d/0x100 kernel/acct.c:192
pin_kill+0x194/0x7c0 fs/fs_pin.c:44
mnt_pin_kill+0x61/0x1e0 fs/fs_pin.c:81
cleanup_mnt+0x3ac/0x450 fs/namespace.c:1366
task_work_run+0x14e/0x250 kernel/task_work.c:239
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0xad8/0x2d70 kernel/exit.c:938
do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
get_signal+0x2576/0x2610 kernel/signal.c:3017
arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f069358473c
Code: Unable to access opcode bytes at 0x7f0693584712.
RSP: 002b:00007ffd01fb5d30 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffe00 RBX: 0000000000000003 RCX: 00007f069358473c
RDX: 0000000000000030 RSI: 00007ffd01fb5de0 RDI: 00000000000000f9
RBP: 00007ffd01fb5d8c R08: 0000000000000000 R09: 0079746972756365
R10: 00007ffd01fb56f0 R11: 0000000000000246 R12: 0000000000000032
R13: 000000000002bc4a R14: 00007ffd01fb5de0 R15: 0000000000000258
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:get_uts kernel/utsname_sysctl.c:23 [inline]
RIP: 0010:proc_do_uts_string+0x137/0x4e0 kernel/utsname_sysctl.c:50
Code: 48 c1 ee 03 80 3c 0e 00 0f 85 56 03 00 00 48 8b 92 08 09 00 00 48 b9 00 00 00 00 00 fc ff df 48 8d 7a 08 48 89 fe 48 c1 ee 03 <80> 3c 0e 00 0f 85 12 03 00 00 48 be 00 00 00 00 00 fc ff df 48 2d
RSP: 0018:ffffc900038f7468 EFLAGS: 00010202
RAX: ffffffff90022485 RBX: 1ffff9200071ee92 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000008
RBP: ffffffff8de39fd8 R08: 0000000000000001 R09: fffffbfff1b8e071
R10: ffffffff8dc7038f R11: 0000000000000002 R12: 0000000000000001
R13: ffffc900038f7520 R14: dffffc0000000000 R15: ffffffff8de39fe0
FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc686ce448 CR3: 000000002f9ae000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 c1 ee 03 shr $0x3,%rsi
4: 80 3c 0e 00 cmpb $0x0,(%rsi,%rcx,1)
8: 0f 85 56 03 00 00 jne 0x364
e: 48 8b 92 08 09 00 00 mov 0x908(%rdx),%rdx
15: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
1c: fc ff df
1f: 48 8d 7a 08 lea 0x8(%rdx),%rdi
23: 48 89 fe mov %rdi,%rsi
26: 48 c1 ee 03 shr $0x3,%rsi
* 2a: 80 3c 0e 00 cmpb $0x0,(%rsi,%rcx,1) <-- trapping instruction
2e: 0f 85 12 03 00 00 jne 0x346
34: 48 be 00 00 00 00 00 movabs $0xdffffc0000000000,%rsi
3b: fc ff df
3e: 48 rex.W
3f: 2d .byte 0x2d

---
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