On 12/31/24 2:10 PM, syzbot wrote:
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=14d4f50f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=86dd15278dbfe19f
dashboard link: https://syzkaller.appspot.com/bug?extid=43f6243d6c4946b26405
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-ccb98cce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/75a6223b351c/vmlinux-ccb98cce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/beea89d50f58/bzImage-ccb98cce.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+43f6243d6c4946b26405@xxxxxxxxxxxxxxxxxxxxxxxxx
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 6a754067 P4D 6a754067 PUD 68142067 PMD 0
Oops: Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 7523 Comm: syz.2.395 Not tainted 6.13.0-rc5-syzkaller-00004-gccb98ccef0e5 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38
Code: e9 44 fd ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f8 48 89 d1 <f3> a4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90
RSP: 0018:ffffc9000370f8b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffc9000370fc50 RCX: 0000000000000004
RDX: 0000000000000004 RSI: ffff88804ef5d710 RDI: 0000000000000000
RBP: 0000000000000004 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000004 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88802b400000(0063) knlGS:00000000f5080b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000006ba72000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
fuse_copy_do fs/fuse/dev.c:809 [inline]
fuse_copy_one+0x1cc/0x230 fs/fuse/dev.c:1065
fuse_copy_args+0x109/0x690 fs/fuse/dev.c:1083
copy_out_args fs/fuse/dev.c:1966 [inline]
fuse_dev_do_write+0x1b0a/0x3100 fs/fuse/dev.c:2052
fuse_dev_write+0x160/0x1f0 fs/fuse/dev.c:2087
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x5ae/0x1150 fs/read_write.c:679
ksys_write+0x12b/0x250 fs/read_write.c:731
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf708e579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5080500 EFLAGS: 00000293 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000700
RDX: 0000000000000014 RSI: 00000000f73c3ff4 RDI: 0000000000000000
RBP: 0000000020008380 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:memcpy+0xc/0x20 arch/x86/lib/memcpy_64.S:38
Code: e9 44 fd ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 48 89 f8 48 89 d1 <f3> a4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90
RSP: 0018:ffffc9000370f8b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffc9000370fc50 RCX: 0000000000000004
RDX: 0000000000000004 RSI: ffff88804ef5d710 RDI: 0000000000000000
RBP: 0000000000000004 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000000 R14: 0000000000000004 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88802b400000(0063) knlGS:00000000f5080b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000006ba72000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: e9 44 fd ff ff jmp 0xfffffd49
5: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
c: 00 00
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 90 nop
19: 90 nop
1a: 90 nop
1b: 90 nop
1c: 90 nop
1d: 90 nop
1e: f3 0f 1e fa endbr64
22: 66 90 xchg %ax,%ax
24: 48 89 f8 mov %rdi,%rax
27: 48 89 d1 mov %rdx,%rcx
* 2a: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
2c: c3 ret
2d: cc int3
2e: cc int3
2f: cc int3
30: cc int3
31: 66 66 2e 0f 1f 84 00 data16 cs nopw 0x0(%rax,%rax,1)
38: 00 00 00 00
3c: 66 90 xchg %ax,%ax
3e: 90 nop
3f: 90 nop
---
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Bug origin in
commit ebe559609d7829b52c6642b581860760984faf9d
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Fri Nov 15 10:30:14 2024 -0500
fs: get rid of __FMODE_NONOTIFY kludge
#syz test
diff --git a/fs/notify/fanotify/fanotify_user.c
b/fs/notify/fanotify/fanotify_user.c
index 19435cd2c41f..6ff94e312232 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1624,8 +1624,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int,
flags, unsigned int, event_f_flags)
file = anon_inode_getfile_fmode("[fanotify]", &fanotify_fops,
group,
f_flags, FMODE_NONOTIFY);
if (IS_ERR(file)) {
- fd = PTR_ERR(file);
put_unused_fd(fd);
+ fd = PTR_ERR(file);
goto out_destroy_group;
}
fd_install(fd, file);
