syzbot
general protection fault in exfat_utf16_to_nls
Status:
fixed on 2025/10/29 21:02
Subsystems:
exfat
[Documentation on labels]
Reported-by: syzbot+3e9cb93e3c5f90d28e19@syzkaller.appspotmail.com
Fix commit:
29c063658d53
exfat: combine iocharset and utf8 option setup
First crash: 304d, last: 304d
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Last patch testing requests (5)
Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 UID: 0 PID: 5982 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:exfat_convert_ucs2_to_char fs/exfat/nls.c:441 [inline]
RIP: 0010:__exfat_utf16_to_nls fs/exfat/nls.c:554 [inline]
RIP: 0010:exfat_utf16_to_nls+0x21c/0x840 fs/exfat/nls.c:638
Code: 2e 29 ff 66 41 83 fc 7f 77 14 e8 7f 2a 29 ff e9 b6 00 00 00 e8 75 2a 29 ff e9 a9 00 00 00 48 8b 4c 24 40 48 89 c8 48 c1 e8 03 <42> 80 3c 38 00 74 0f 48 8b 7c 24 40 e8 d3 6b 8e ff 48 8b 4c 24 40
RSP: 0018:ffffc90003c9f760 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000004 RCX: 0000000000000010
RDX: ffff8880310f9e40 RSI: 00000000000000e1 RDI: 0000000000000080
RBP: ffffc90003c9f850 R08: 0000000000000005 R09: 0000000000000000
R10: ffffc90003c9f7e0 R11: fffff52000793efc R12: 00000000000000e1
R13: ffffc90003c9fa48 R14: 0000000000000000 R15: dffffc0000000000
FS: 000055556520c500(0000) GS:ffff888125a03000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055556522f608 CR3: 0000000079d18000 CR4: 00000000003526f0
Call Trace:
<TASK>
exfat_readdir fs/exfat/dir.c:143 [inline]
exfat_iterate+0x19a7/0x2050 fs/exfat/dir.c:243
wrap_directory_iterator+0x96/0xe0 fs/readdir.c:65
iterate_dir+0x399/0x570 fs/readdir.c:108
__do_sys_getdents64 fs/readdir.c:410 [inline]
__se_sys_getdents64+0xe4/0x260 fs/readdir.c:396
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff17b9c1833
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 32 3d f8 ff 66 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 a8 ff ff ff f7 d8
RSP: 002b:00007fff3d1c29f8 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000555565227600 RCX: 00007ff17b9c1833
RDX: 0000000000008000 RSI: 0000555565227600 RDI: 0000000000000005
RBP: 00005555652275d4 R08: 0000000000028a41 R09: 0000000000000000
R10: 00007ff17bbb7cc0 R11: 0000000000000293 R12: ffffffffffffffa8
R13: 0000000000000010 R14: 00005555652275d0 R15: 00007fff3d1c4cb0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:exfat_convert_ucs2_to_char fs/exfat/nls.c:441 [inline]
RIP: 0010:__exfat_utf16_to_nls fs/exfat/nls.c:554 [inline]
RIP: 0010:exfat_utf16_to_nls+0x21c/0x840 fs/exfat/nls.c:638
Code: 2e 29 ff 66 41 83 fc 7f 77 14 e8 7f 2a 29 ff e9 b6 00 00 00 e8 75 2a 29 ff e9 a9 00 00 00 48 8b 4c 24 40 48 89 c8 48 c1 e8 03 <42> 80 3c 38 00 74 0f 48 8b 7c 24 40 e8 d3 6b 8e ff 48 8b 4c 24 40
RSP: 0018:ffffc90003c9f760 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000004 RCX: 0000000000000010
RDX: ffff8880310f9e40 RSI: 00000000000000e1 RDI: 0000000000000080
RBP: ffffc90003c9f850 R08: 0000000000000005 R09: 0000000000000000
R10: ffffc90003c9f7e0 R11: fffff52000793efc R12: 00000000000000e1
R13: ffffc90003c9fa48 R14: 0000000000000000 R15: dffffc0000000000
FS: 000055556520c500(0000) GS:ffff888125a03000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c007d08000 CR3: 0000000079d18000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 2e 29 ff cs sub %edi,%edi
3: 66 41 83 fc 7f cmp $0x7f,%r12w
8: 77 14 ja 0x1e
a: e8 7f 2a 29 ff call 0xff292a8e
f: e9 b6 00 00 00 jmp 0xca
14: e8 75 2a 29 ff call 0xff292a8e
19: e9 a9 00 00 00 jmp 0xc7
1e: 48 8b 4c 24 40 mov 0x40(%rsp),%rcx
23: 48 89 c8 mov %rcx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction
2f: 74 0f je 0x40
31: 48 8b 7c 24 40 mov 0x40(%rsp),%rdi
36: e8 d3 6b 8e ff call 0xff8e6c0e
3b: 48 8b 4c 24 40 mov 0x40(%rsp),%rcx
Struck through repros no longer work on HEAD.