general protection fault in rtc_dev_ioctl

Status: upstream: reported C repro on 2026/10/26 16:10
Reported-by: syzbot+adc43c7d3d8e60666e84@syzkaller.appspotmail.com
First crash: 5d14h, last: 5d09h
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 general protection fault in rtc_dev_ioctl 2 syz, C 5 1d02h 31d 0/2 upstream: reported C repro on 2026/09/30 11:22
android-6-12 general protection fault in rtc_dev_ioctl 2 syz, C 3 22d 22d 0/1 premoderation: reported C repro on 2026/10/09 22:33

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 303 Comm: syz-executor374 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:rtc_dev_ioctl+0x7b9/0x930 drivers/rtc/dev.c:387
Code: 85 f6 0f 84 d5 00 00 00 e8 a4 44 27 fe 48 c7 c0 f2 ff ff ff e9 b7 f9 ff ff e8 93 44 27 fe 4c 8b 74 24 38 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 f8 cc 66 fe 4d 8b 36 4d 85 f6 74
RSP: 0018:ffffc900009a7d20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88810bc22000 RCX: ffff8881063ca800
RDX: 0000000000000000 RSI: ffffffff86b9bcb0 RDI: 000000008004f50c
RBP: ffffc900009a7e80 R08: ffff8881063ca800 R09: 000000000000000f
R10: 0000000080287010 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffff92000134fac R14: 0000000000000000 R15: dffffc0000000000
FS:  0000555586c3b3c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000062b5d8 CR3: 000000011fefd000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:860
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:860
 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f7ab6fc1cf9
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:00007ffc269e7e48 EFLAGS: 00000246
 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffc269e7f78 RCX: 00007f7ab6fc1cf9
RDX: 0000000000000000 RSI: 000000008004f50c RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffc269e7f78 R09: 00007ffc269e7f78
R10: 00007ffc269e7f78 R11: 0000000000000246 R12: 00007ffc269e7f68
R13: 0000000000000002 R14: 00007f7ab7052ca0 R15: 0000000000000002
 </TASK>
Modules linked in:
---[ end trace 3fd15d17e97c7343 ]---
RIP: 0010:rtc_dev_ioctl+0x7b9/0x930 drivers/rtc/dev.c:387
Code: 85 f6 0f 84 d5 00 00 00 e8 a4 44 27 fe 48 c7 c0 f2 ff ff ff e9 b7 f9 ff ff e8 93 44 27 fe 4c 8b 74 24 38 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 f8 cc 66 fe 4d 8b 36 4d 85 f6 74
RSP: 0018:ffffc900009a7d20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88810bc22000 RCX: ffff8881063ca800
RDX: 0000000000000000 RSI: ffffffff86b9bcb0 RDI: 000000008004f50c
RBP: ffffc900009a7e80 R08: ffff8881063ca800 R09: 000000000000000f
R10: 0000000080287010 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffff92000134fac R14: 0000000000000000 R15: dffffc0000000000
FS:  0000555586c3b3c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000062b5d8 CR3: 000000011fefd000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	85 f6                	test   %esi,%esi
   2:	0f 84 d5 00 00 00    	je     0xdd
   8:	e8 a4 44 27 fe       	call   0xfe2744b1
   d:	48 c7 c0 f2 ff ff ff 	mov    $0xfffffffffffffff2,%rax
  14:	e9 b7 f9 ff ff       	jmp    0xfffff9d0
  19:	e8 93 44 27 fe       	call   0xfe2744b1
  1e:	4c 8b 74 24 38       	mov    0x38(%rsp),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 f8 cc 66 fe       	call   0xfe66cd31
  39:	4d 8b 36             	mov    (%r14),%r14
  3c:	4d 85 f6             	test   %r14,%r14
  3f:	74                   	.byte 0x74

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/26 21:16 android13-5.15-lts dde14ee8fb2e 168cb7a2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in rtc_dev_ioctl
2026/10/26 20:42 android13-5.15-lts dde14ee8fb2e 168cb7a2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in rtc_dev_ioctl
2026/10/26 16:09 android13-5.15-lts dde14ee8fb2e 168cb7a2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in rtc_dev_ioctl
* Struck through repros no longer work on HEAD.