[syzbot] [overlayfs?] general protection fault in ovl_encode_real_fh
From: syzbot
Date: Mon Oct 02 2023 - 19:39:20 EST
Hello,
syzbot found the following issue on:
HEAD commit: 8a749fd1a872 Linux 6.6-rc4
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=154d1e92680000
kernel config: https://syzkaller.appspot.com/x/.config?x=57da1ac039c4c78a
dashboard link: https://syzkaller.appspot.com/bug?extid=2208f82282740c1c8915
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14877eb2680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13b701f6680000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fffd72e2263d/disk-8a749fd1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0645b67d82dc/vmlinux-8a749fd1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/135b10b98a67/bzImage-8a749fd1.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2208f82282740c1c8915@xxxxxxxxxxxxxxxxxxxxxxxxx
general protection fault, probably for non-canonical address 0xdffffc000000001c: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000e0-0x00000000000000e7]
CPU: 1 PID: 5028 Comm: syz-executor194 Not tainted 6.6.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
RIP: 0010:ovl_encode_real_fh+0x87/0x400 fs/overlayfs/copy_up.c:380
Code: 20 49 c1 ee 03 48 b8 f1 f1 f1 f1 04 f3 f3 f3 49 89 04 1e e8 1b e5 8b fe 48 89 d9 49 8d 9c 24 e0 00 00 00 48 89 d8 48 c1 e8 03 <80> 3c 08 00 74 12 48 89 df e8 0b 61 e6 fe 48 b9 00 00 00 00 00 fc
RSP: 0018:ffffc900039efc80 EFLAGS: 00010202
RAX: 000000000000001c RBX: 00000000000000e0 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880132ab500
RBP: ffffc900039efd30 R08: ffffffff8302916f R09: 1ffff1100ed51471
R10: dffffc0000000000 R11: ffffed100ed51472 R12: 0000000000000000
R13: ffff8880132ab500 R14: 1ffff9200073df94 R15: ffff888078f34758
FS: 0000555556705380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001000 CR3: 000000001bfb2000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ovl_dentry_to_fid fs/overlayfs/export.c:240 [inline]
ovl_encode_fh+0x2ac/0xc70 fs/overlayfs/export.c:275
exportfs_encode_inode_fh fs/exportfs/expfs.c:407 [inline]
exportfs_encode_fh+0x195/0x490 fs/exportfs/expfs.c:438
do_sys_name_to_handle fs/fhandle.c:52 [inline]
__do_sys_name_to_handle_at fs/fhandle.c:116 [inline]
__se_sys_name_to_handle_at+0x3ad/0x730 fs/fhandle.c:98
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f37d63e4429
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd5eea5b98 EFLAGS: 00000246 ORIG_RAX: 000000000000012f
RAX: ffffffffffffffda RBX: 00007ffd5eea5d68 RCX: 00007f37d63e4429
RDX: 0000000020000300 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 00007f37d6457610 R08: 0000000000001600 R09: 00007ffd5eea5d68
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffd5eea5d58 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ovl_encode_real_fh+0x87/0x400 fs/overlayfs/copy_up.c:380
Code: 20 49 c1 ee 03 48 b8 f1 f1 f1 f1 04 f3 f3 f3 49 89 04 1e e8 1b e5 8b fe 48 89 d9 49 8d 9c 24 e0 00 00 00 48 89 d8 48 c1 e8 03 <80> 3c 08 00 74 12 48 89 df e8 0b 61 e6 fe 48 b9 00 00 00 00 00 fc
RSP: 0018:ffffc900039efc80 EFLAGS: 00010202
RAX: 000000000000001c RBX: 00000000000000e0 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880132ab500
RBP: ffffc900039efd30 R08: ffffffff8302916f R09: 1ffff1100ed51471
R10: dffffc0000000000 R11: ffffed100ed51472 R12: 0000000000000000
R13: ffff8880132ab500 R14: 1ffff9200073df94 R15: ffff888078f34758
FS: 0000555556705380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001000 CR3: 000000001bfb2000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 20 49 c1 and %cl,-0x3f(%rcx)
3: ee out %al,(%dx)
4: 03 48 b8 add -0x48(%rax),%ecx
7: f1 int1
8: f1 int1
9: f1 int1
a: f1 int1
b: 04 f3 add $0xf3,%al
d: f3 f3 49 89 04 1e repz xrelease mov %rax,(%r14,%rbx,1)
13: e8 1b e5 8b fe call 0xfe8be533
18: 48 89 d9 mov %rbx,%rcx
1b: 49 8d 9c 24 e0 00 00 lea 0xe0(%r12),%rbx
22: 00
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 74 12 je 0x42
30: 48 89 df mov %rbx,%rdi
33: e8 0b 61 e6 fe call 0xfee66143
38: 48 rex.W
39: b9 00 00 00 00 mov $0x0,%ecx
3e: 00 fc add %bh,%ah
---
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