UBSAN: array-index-out-of-bounds in xtSearch

Status: fixed on 2023/09/23 10:26
Bug presence: origin:upstream
[Documentation on labels]
Fix commit: f27f759f4cd4 jfs: validate max amount of blocks before allocation.
First crash: 155d, last: 78d
Fix bisection: fixed by (bisect log) :
commit f27f759f4cd490593cc7527b03fcec3aa4dbc2e7
Author: Alexei Filippov <>
Date: Sat Aug 19 17:32:16 2023 +0000

  jfs: validate max amount of blocks before allocation.

Bug presence (1)
Date Name Commit Repro Result
2023/07/09 upstream (ToT) 1c7873e33645 C [report] UBSAN: array-index-out-of-bounds in xtSearch
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream UBSAN: array-index-out-of-bounds in xtSearch jfs C unreliable 109 8h45m 356d 0/25 upstream: reported C repro on 2022/10/04 08:50
linux-5.15 UBSAN: array-index-out-of-bounds in xtSearch 17 150d 193d 0/3 auto-obsoleted due to no activity on 2023/08/22 15:17

Sample crash report:
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_xtree.c:360:4
index 19 is out of range for type 'xad_t[18]' (aka 'struct xad[18]')
CPU: 0 PID: 3712 Comm: syz-executor194 Not tainted 6.1.38-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_out_of_bounds+0x118/0x140 lib/ubsan.c:282
 xtSearch+0x6dc/0x1ca0 fs/jfs/jfs_xtree.c:360
 xtLookup+0x2c0/0x8e0 fs/jfs/jfs_xtree.c:152
 jfs_get_block+0x2e5/0xe50 fs/jfs/inode.c:218
 do_mpage_readpage+0x8d2/0x2040 fs/mpage.c:208
 mpage_readahead+0x450/0x920 fs/mpage.c:361
 read_pages+0x17f/0x830 mm/readahead.c:161
 page_cache_ra_unbounded+0x68b/0x7b0 mm/readahead.c:270
 filemap_readahead mm/filemap.c:2557 [inline]
 filemap_get_pages mm/filemap.c:2598 [inline]
 filemap_read+0xaad/0x31d0 mm/filemap.c:2676
 call_read_iter include/linux/fs.h:2199 [inline]
 generic_file_splice_read+0x23c/0x630 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x408/0xbd0 fs/splice.c:865
 do_splice_direct+0x27f/0x3c0 fs/splice.c:974
 do_sendfile+0x61c/0xff0 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1309
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
RIP: 0033:0x7f6725857b89
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 15 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f67257f21f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f67258e57e8 RCX: 00007f6725857b89
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000009
RBP: 00007f67258e57e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201004 R11: 0000000000000246 R12: 00007f67258e57ec
R13: 00007ffe66064edf R14: 00007f67257f2300 R15: 0000000000022000

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/09 02:42 linux-6.1.y 61fd484b2cf6 668cb1fa .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan UBSAN: array-index-out-of-bounds in xtSearch
2023/05/22 13:56 linux-6.1.y fa74641fb6b9 4bce1a3e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: array-index-out-of-bounds in xtSearch
2023/04/22 19:34 linux-6.1.y f17b0ab65d17 2b32bd34 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 UBSAN: array-index-out-of-bounds in xtSearch
* Struck through repros no longer work on HEAD.