syzbot


general protection fault in ksm_do_scan

Status: moderation: reported on 2024/07/05 06:20
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+a80d44d3b2f47462bd2b@syzkaller.appspotmail.com
First crash: 12d, last: 6d01h

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000084: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000420-0x0000000000000427]
CPU: 0 PID: 36 Comm: ksmd Not tainted 6.10.0-rc6-syzkaller-00215-g22f902dfc51e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:scan_get_next_rmap_item mm/ksm.c:2647 [inline]
RIP: 0010:ksm_do_scan+0x79c/0x6860 mm/ksm.c:2759
Code: 89 e7 48 c7 c6 ff ff ff ff e8 20 6a 80 09 49 89 c6 48 85 c0 4c 89 7c 24 60 0f 84 b9 0a 00 00 49 8d 5e 20 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 d5 5e 01 00 48 8b 1b be 00 00 00
RSP: 0018:ffffc90000ac7b40 EFLAGS: 00010217
RAX: 0000000000000084 RBX: 0000000000000426 RCX: ffff8880186fda00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000ac7d90 R08: ffffffff8b7abdb4 R09: ffffffff8b7abc39
R10: 0000000000000004 R11: ffff8880186fda00 R12: ffffc90000ac7ce0
R13: dffffc0000000000 R14: 0000000000000406 R15: ffff88807e340a44
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002003b000 CR3: 000000007994c000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 ksm_scan_thread+0x110/0x490 mm/ksm.c:2784
 kthread+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:scan_get_next_rmap_item mm/ksm.c:2647 [inline]
RIP: 0010:ksm_do_scan+0x79c/0x6860 mm/ksm.c:2759
Code: 89 e7 48 c7 c6 ff ff ff ff e8 20 6a 80 09 49 89 c6 48 85 c0 4c 89 7c 24 60 0f 84 b9 0a 00 00 49 8d 5e 20 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 d5 5e 01 00 48 8b 1b be 00 00 00
RSP: 0018:ffffc90000ac7b40 EFLAGS: 00010217
RAX: 0000000000000084 RBX: 0000000000000426 RCX: ffff8880186fda00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000ac7d90 R08: ffffffff8b7abdb4 R09: ffffffff8b7abc39
R10: 0000000000000004 R11: ffff8880186fda00 R12: ffffc90000ac7ce0
R13: dffffc0000000000 R14: 0000000000000406 R15: ffff88807e340a44
FS:  0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b320faff8 CR3: 0000000066b36000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
   0:	89 e7                	mov    %esp,%edi
   2:	48 c7 c6 ff ff ff ff 	mov    $0xffffffffffffffff,%rsi
   9:	e8 20 6a 80 09       	call   0x9806a2e
   e:	49 89 c6             	mov    %rax,%r14
  11:	48 85 c0             	test   %rax,%rax
  14:	4c 89 7c 24 60       	mov    %r15,0x60(%rsp)
  19:	0f 84 b9 0a 00 00    	je     0xad8
  1f:	49 8d 5e 20          	lea    0x20(%r14),%rbx
  23:	48 89 d8             	mov    %rbx,%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:	48 89 df             	mov    %rbx,%rdi
  34:	e8 d5 5e 01 00       	call   0x15f0e
  39:	48 8b 1b             	mov    (%rbx),%rbx
  3c:	be                   	.byte 0xbe
  3d:	00 00                	add    %al,(%rax)

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/07 09:54 upstream 22f902dfc51e bc4ebbb5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root general protection fault in ksm_do_scan
2024/07/01 06:11 upstream 3ffea9a7a6f7 757f06b1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in ksm_do_scan
* Struck through repros no longer work on HEAD.