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KASAN: null-ptr-deref Write in backing_data_changed

Status: fixed on 2023/12/20 15:24
Bug presence: origin:downstream
[Documentation on labels]
Reported-by: syzbot+c5dd3082fd6efa062072@syzkaller.appspotmail.com
Fix commit: e89b1266f784 ANDROID: fuse-bpf: Add NULL pointer check in fuse_entry_revalidate
First crash: 229d, last: 165d
Fix bisection: fixed by (bisect log) :
commit e89b1266f784b2271af2e72a5d04e3e39d0afcdc
Author: liujinbao1 <liujinbao1@xiaomi.corp-partner.google.com>
Date: Thu Oct 12 04:28:06 2023 +0000

  ANDROID: fuse-bpf: Add NULL pointer check in fuse_entry_revalidate

  
▶ ▼ Bug presence (3)
Date Name Commit Repro Result
2023/09/16 android13-5.15-lts (ToT) ea586874d2f9 C [report] KASAN: null-ptr-deref Write in backing_data_changed
2023/09/16 lts (merge base) aff03380bda4 C Didn't crash
2023/09/16 upstream (ToT) 57d88e8a5974 C Didn't crash
▶ ▼ Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: null-ptr-deref Write in backing_data_changed C done 3 184d 256d 0/2 auto-obsoleted due to no activity on 2024/02/08 13:32
android-6-1 KASAN: null-ptr-deref Write in backing_data_changed origin:downstream C done done 1 219d 256d 0/2 auto-obsoleted due to no activity on 2024/01/04 12:03
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2023/12/19 10:36 2h56m bisect fix android13-5.15-lts job log (1)
2023/11/19 04:42 36m bisect fix android13-5.15-lts job log (0) log
2023/10/18 17:37 37m bisect fix android13-5.15-lts job log (0) log

Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in atomic_inc_return include/linux/atomic/atomic-instrumented.h:188 [inline]
BUG: KASAN: null-ptr-deref in ihold+0x20/0x60 fs/inode.c:426
Write of size 4 at addr 0000000000000170 by task syz-executor267/296

CPU: 0 PID: 296 Comm: syz-executor267 Not tainted 5.15.131-syzkaller-00653-gea586874d2f9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 __kasan_report mm/kasan/report.c:431 [inline]
 kasan_report+0x16f/0x1c0 mm/kasan/report.c:444
 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_inc_return include/linux/atomic/atomic-instrumented.h:188 [inline]
 ihold+0x20/0x60 fs/inode.c:426
 backing_data_changed+0x1d9/0x4f0 fs/fuse/dir.c:196
 fuse_dentry_revalidate+0x826/0xe70 fs/fuse/dir.c:306
 d_revalidate fs/namei.c:854 [inline]
 lookup_dcache fs/namei.c:1524 [inline]
 __lookup_hash+0x1b3/0x290 fs/namei.c:1545
 do_renameat2+0x671/0x1480 fs/namei.c:4843
 __do_sys_rename fs/namei.c:4938 [inline]
 __se_sys_rename fs/namei.c:4936 [inline]
 __x64_sys_rename+0x86/0x90 fs/namei.c:4936
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f1878cdc739
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1878c7d218 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f1878d6b3f8 RCX: 00007f1878cdc739
RDX: 00007f1878cdc739 RSI: 0000000020000140 RDI: 0000000020000100
RBP: 00007f1878d6b3f0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1878d3809c
R13: 000000000000006e R14: 0030656c69662f30 R15: 00007f1878d36098
 </TASK>
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000170
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 11d1fe067 P4D 11d1fe067 PUD 11d1ff067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 296 Comm: syz-executor267 Tainted: G    B             5.15.131-syzkaller-00653-gea586874d2f9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
RIP: 0010:arch_atomic_inc_return include/linux/atomic/atomic-arch-fallback.h:370 [inline]
RIP: 0010:atomic_inc_return include/linux/atomic/atomic-instrumented.h:189 [inline]
RIP: 0010:ihold+0x25/0x60 fs/inode.c:426
Code: 00 00 00 00 00 55 48 89 e5 41 56 53 49 89 fe e8 e1 0f af ff 49 8d be 70 01 00 00 be 04 00 00 00 e8 70 fd f0 ff bb 01 00 00 00 <f0> 41 0f c1 9e 70 01 00 00 ff c3 bf 02 00 00 00 89 de e8 64 13 af
RSP: 0018:ffffc90000987800 EFLAGS: 00010246
RAX: ffff88811e282700 RBX: 0000000000000001 RCX: ffff88811e282780
RDX: 0000000000000000 RSI: 0000000000000292 RDI: 00000000ffffffff
RBP: ffffc90000987810 R08: ffffffff81416a8b R09: 0000000000000003
R10: fffffbfff0e51e4c R11: dffffc0000000001 R12: ffffc900009878a0
R13: 1ffff92000130f0c R14: 0000000000000000 R15: ffff88811b97d100
FS:  00007f1878c7d6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000170 CR3: 000000011d1f5000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 backing_data_changed+0x1d9/0x4f0 fs/fuse/dir.c:196
 fuse_dentry_revalidate+0x826/0xe70 fs/fuse/dir.c:306
 d_revalidate fs/namei.c:854 [inline]
 lookup_dcache fs/namei.c:1524 [inline]
 __lookup_hash+0x1b3/0x290 fs/namei.c:1545
 do_renameat2+0x671/0x1480 fs/namei.c:4843
 __do_sys_rename fs/namei.c:4938 [inline]
 __se_sys_rename fs/namei.c:4936 [inline]
 __x64_sys_rename+0x86/0x90 fs/namei.c:4936
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f1878cdc739
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1878c7d218 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f1878d6b3f8 RCX: 00007f1878cdc739
RDX: 00007f1878cdc739 RSI: 0000000020000140 RDI: 0000000020000100
RBP: 00007f1878d6b3f0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1878d3809c
R13: 000000000000006e R14: 0030656c69662f30 R15: 00007f1878d36098
 </TASK>
Modules linked in:
CR2: 0000000000000170
---[ end trace 17ede772bae89d41 ]---
RIP: 0010:arch_atomic_inc_return include/linux/atomic/atomic-arch-fallback.h:370 [inline]
RIP: 0010:atomic_inc_return include/linux/atomic/atomic-instrumented.h:189 [inline]
RIP: 0010:ihold+0x25/0x60 fs/inode.c:426
Code: 00 00 00 00 00 55 48 89 e5 41 56 53 49 89 fe e8 e1 0f af ff 49 8d be 70 01 00 00 be 04 00 00 00 e8 70 fd f0 ff bb 01 00 00 00 <f0> 41 0f c1 9e 70 01 00 00 ff c3 bf 02 00 00 00 89 de e8 64 13 af
RSP: 0018:ffffc90000987800 EFLAGS: 00010246
RAX: ffff88811e282700 RBX: 0000000000000001 RCX: ffff88811e282780
RDX: 0000000000000000 RSI: 0000000000000292 RDI: 00000000ffffffff
RBP: ffffc90000987810 R08: ffffffff81416a8b R09: 0000000000000003
R10: fffffbfff0e51e4c R11: dffffc0000000001 R12: ffffc900009878a0
R13: 1ffff92000130f0c R14: 0000000000000000 R15: ffff88811b97d100
FS:  00007f1878c7d6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000170 CR3: 000000011d1f5000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 00                	add    %al,(%rax)
   4:	00 55 48             	add    %dl,0x48(%rbp)
   7:	89 e5                	mov    %esp,%ebp
   9:	41 56                	push   %r14
   b:	53                   	push   %rbx
   c:	49 89 fe             	mov    %rdi,%r14
   f:	e8 e1 0f af ff       	call   0xffaf0ff5
  14:	49 8d be 70 01 00 00 	lea    0x170(%r14),%rdi
  1b:	be 04 00 00 00       	mov    $0x4,%esi
  20:	e8 70 fd f0 ff       	call   0xfff0fd95
  25:	bb 01 00 00 00       	mov    $0x1,%ebx
* 2a:	f0 41 0f c1 9e 70 01 	lock xadd %ebx,0x170(%r14) <-- trapping instruction
  31:	00 00
  33:	ff c3                	inc    %ebx
  35:	bf 02 00 00 00       	mov    $0x2,%edi
  3a:	89 de                	mov    %ebx,%esi
  3c:	e8                   	.byte 0xe8
  3d:	64                   	fs
  3e:	13                   	.byte 0x13
  3f:	af                   	scas   %es:(%rdi),%eax

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/09/16 11:26 android13-5.15-lts ea586874d2f9 0b6a67ac .config strace log report syz C [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: null-ptr-deref Write in backing_data_changed
* Struck through repros no longer work on HEAD.