[syzbot] [jfs?] UBSAN: array-index-out-of-bounds in dbAllocAG

[syzbot] [jfs?] UBSAN: array-index-out-of-bounds in dbAllocAG

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    8560697b23dc Merge tag '6.15-rc2-smb3-client-fixes' of git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=133fbbac580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2a31f7155996562
dashboard link: https://syzkaller.appspot.com/bug?extid=cffd18309153948f3c3e
compiler:       Debian clang version 15.0.6, Debian LLD 15.0.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14708c70580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=115dd204580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-8560697b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2acea3e6b668/vmlinux-8560697b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d2542a0d2bcd/bzImage-8560697b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/2b4250dbd0ba/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=10708c70580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cffd18309153948f3c3e@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:1397:14
index 65877 is out of range for type 's8[1365]' (aka 'signed char[1365]')
CPU: 0 UID: 0 PID: 5308 Comm: syz-executor181 Not tainted 6.15.0-rc2-syzkaller-00404-g8560697b23dc #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:453
 dbAllocAG+0x704/0x1130 fs/jfs/jfs_dmap.c:1397
 dbAlloc+0x65c/0xcb0 fs/jfs/jfs_dmap.c:873
 xtSplitUp+0x554/0x21c0 fs/jfs/jfs_xtree.c:745
 xtInsert+0x5ba/0x11a0 fs/jfs/jfs_xtree.c:593
 extAlloc+0xae7/0x10a0 fs/jfs/jfs_extent.c:150
 jfs_get_block+0x41d/0xe60 fs/jfs/inode.c:248
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x1add/0x4540 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3422 [inline]
 jfs_direct_IO+0xf7/0x1e0 fs/jfs/inode.c:331
 generic_file_direct_write+0x1e8/0x400 mm/filemap.c:4037
 __generic_file_write_iter+0x126/0x230 mm/filemap.c:4206
 generic_file_write_iter+0x10e/0x5e0 mm/filemap.c:4246
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x70f/0xd10 fs/read_write.c:684
 ksys_write+0x19d/0x2d0 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2346650b59
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffd3c588a8 EFLAGS: 00000206 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0073746e6576652e RCX: 00007f2346650b59
RDX: 00000000fffffdaf RSI: 0000200000000000 RDI: 0000000000000005
RBP: 652e79726f6d656d R08: 00005555682c24c0 R09: 00005555682c24c0
R10: 00005555682c24c0 R11: 0000000000000206 R12: 00007fffd3c588d0
R13: 00007fffd3c58af8 R14: 431bde82d7b634db R15: 00007f234669903b
 </TASK>
---[ end trace ]---


---
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syztest

[Arnaud Lecomte]

#syz test

--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1385,6 +1385,12 @@ dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
            (1 << (L2LPERCTL - (bmp->db_agheight << 1))) / bmp->db_agwidth;
        ti = bmp->db_agstart + bmp->db_agwidth * (agno & (agperlev - 1));
 
+       if (ti >= le32_to_cpu(dcp->nleafs)) {
+               jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmapctl page: ti out of bounds\n");
+               release_metapage(mp);
+               return -EIO;
+       }
+
        /* dmap control page trees fan-out by 4 and a single allocation
         * group may be described by 1 or 2 subtrees within the ag level
         * dmap control page, depending upon the ag size. examine the ag's

Re: [syzbot] [jfs?] UBSAN: array-index-out-of-bounds in dbAllocAG

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+cffd18309153948f3c3e@syzkaller.appspotmail.com
Tested-by: syzbot+cffd18309153948f3c3e@syzkaller.appspotmail.com

Tested on:

commit:         a79be02b Fix mis-uses of 'cc-option' for warning disab..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=120ae574580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=45c3bf6fd4cb6a10
dashboard link: https://syzkaller.appspot.com/bug?extid=cffd18309153948f3c3e
compiler:       Debian clang version 15.0.6, Debian LLD 15.0.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1252e574580000

Note: testing is done by a robot and is best-effort only.