[syzbot] [ocfs2?] KASAN: use-after-free Read in ocfs2_search_extent_list

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5076001689e4 Merge tag 'loongarch-fixes-6.13-1' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=120f68df980000
kernel config: https://syzkaller.appspot.com/x/.config?x=50c7a61469ce77e7
dashboard link: https://syzkaller.appspot.com/bug?extid=2313dda4dc4885c93578
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=13b29330580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17b29330580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-50760016.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/76ef343a98c8/vmlinux-50760016.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e42b3235bcc3/bzImage-50760016.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/893e4e85ff3d/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2313dd...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
JBD2: Ignoring recovery information on journal
==================================================================
BUG: KASAN: use-after-free in ocfs2_search_extent_list+0x155/0x200 fs/ocfs2/alloc.c:776
Read of size 4 at addr ffff888049800000 by task syz-executor307/5410

CPU: 0 UID: 0 PID: 5410 Comm: syz-executor307 Not tainted 6.13.0-rc1-syzkaller-00036-g5076001689e4 #0
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
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x169/0x550 mm/kasan/report.c:489
kasan_report+0x143/0x180 mm/kasan/report.c:602
ocfs2_search_extent_list+0x155/0x200 fs/ocfs2/alloc.c:776
ocfs2_get_clusters_nocache+0x21a/0xbf0 fs/ocfs2/extent_map.c:438
ocfs2_get_clusters+0x5bd/0xbd0 fs/ocfs2/extent_map.c:621
ocfs2_extent_map_get_blocks+0x24c/0x7d0 fs/ocfs2/extent_map.c:668
ocfs2_bmap+0x2b7/0x780 fs/ocfs2/aops.c:474
bmap+0xa8/0xe0 fs/inode.c:1997
jbd2_journal_bmap+0x12d/0x2b0 fs/jbd2/journal.c:926
do_readahead fs/jbd2/recovery.c:88 [inline]
jread+0x435/0xc80 fs/jbd2/recovery.c:165
do_one_pass+0x3cd/0x3aa0 fs/jbd2/recovery.c:646
jbd2_journal_skip_recovery+0x95/0x240 fs/jbd2/recovery.c:366
jbd2_journal_wipe+0xc9/0x110 fs/jbd2/journal.c:2517
ocfs2_journal_wipe+0xab/0x2a0 fs/ocfs2/journal.c:1192
ocfs2_check_volume fs/ocfs2/super.c:2413 [inline]
ocfs2_mount_volume+0xb86/0x1940 fs/ocfs2/super.c:1817
ocfs2_fill_super+0x476e/0x5760 fs/ocfs2/super.c:1084
mount_bdev+0x20a/0x2d0 fs/super.c:1693
legacy_get_tree+0xee/0x190 fs/fs_context.c:662
vfs_get_tree+0x90/0x2b0 fs/super.c:1814
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4057 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdc66ec71aa
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007ffee9a2de18 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffee9a2de30 RCX: 00007fdc66ec71aa
RDX: 0000000020004440 RSI: 0000000020000040 RDI: 00007ffee9a2de30
RBP: 0000000000000004 R08: 00007ffee9a2de70 R09: 0000000000004431
R10: 00000000000008c0 R11: 0000000000000282 R12: 00000000000008c0
R13: 00007ffee9a2de70 R14: 0000000000000003 R15: 0000000001000000
</TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x49800
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 04fff00000000000 ffff88805ffd7230 ffff88805ffd7230 0000000000000000
raw: 0000000000000000 000000000000000a 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
ffff8880497fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880497fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888049800000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888049800080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888049800100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Edward Adam Davis]

#syz test: https://github.com/ea1davis/linux ocfs2/syz

[Julian Sun]

On Mon, 2024-12-09 at 15:04 -0800, syzbot wrote:

Add a sanity check for corrupted file system images.

#syz test: upstream 5076001689e4

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 2cc5c99fe941..60c84049f3e4 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1358,6 +1358,21 @@ void ocfs2_refresh_inode(struct inode *inode,
spin_unlock(&OCFS2_I(inode)->ip_lock);
}

+static int has_extents(struct ocfs2_dinode *di)
+{
+ /* inodes flagged with other stuff in id2 */
+ if (di->i_flags & (OCFS2_SUPER_BLOCK_FL | OCFS2_LOCAL_ALLOC_FL |
+ OCFS2_CHAIN_FL | OCFS2_DEALLOC_FL))
+ return 0;
+ /* i_flags doesn't indicate when id2 is a fast symlink */
+ if (S_ISLNK(di->i_mode) && di->i_size && di->i_clusters == 0)
+ return 0;
+ if (di->i_dyn_features & OCFS2_INLINE_DATA_FL)
+ return 0;
+
+ return 1;
+}
+
int ocfs2_validate_inode_block(struct super_block *sb,
struct buffer_head *bh)
{
@@ -1386,6 +1401,15 @@ int ocfs2_validate_inode_block(struct super_block *sb,

rc = -EINVAL;

+ if (has_extents(di) &&
+ le16_to_cpu(di->id2.i_list.l_next_free_rec) > le16_to_cpu(di->id2.i_list.l_count)) {
+ rc = ocfs2_error(sb, "corrupted dinode #%llu: next_free_rec is %u, count is %u\n",
+ (unsigned long long)bh->b_blocknr,
+ le16_to_cpu(di->id2.i_list.l_next_free_rec),
+ le16_to_cpu(di->id2.i_list.l_count));
+ goto bail;
+ }
+
if (!OCFS2_IS_VALID_DINODE(di)) {
rc = ocfs2_error(sb, "Invalid dinode #%llu: signature = %.*s\n",
(unsigned long long)bh->b_blocknr, 7,

--
Julian Sun <sunjunc...@gmail.com>

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: Re: KASAN: use-after-free Read in ocfs2_search_extent_list()
Author: dman...@yandex.ru

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 7cb1b466315004af98f6ba6c2546bb713ca3c237

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 395e23920632..841135341898 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -770,6 +770,10 @@ int ocfs2_search_extent_list(struct ocfs2_extent_list *el, u32 v_cluster)
struct ocfs2_extent_rec *rec;
u32 rec_end, rec_start, clusters;

+ /* Do not search over an invalid extent list. */
+ if (le16_to_cpu(el->l_next_free_rec) >= le16_to_cpu(el->l_count))
+ return ret;
+
for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
rec = &el->l_recs[i];

[syzbot]

Hello,

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

Reported-by: syzbot+2313dd...@syzkaller.appspotmail.com
Tested-by: syzbot+2313dd...@syzkaller.appspotmail.com

Tested on:

commit: 6ddd5d53 ocfs2: Take the smaller of l_next_free_rec an..
git tree: https://github.com/ea1davis/linux ocfs2/syz
console output: https://syzkaller.appspot.com/x/log.txt?x=145d7c0f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=82d76f5a1a8b5c36

dashboard link: https://syzkaller.appspot.com/bug?extid=2313dda4dc4885c93578
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

[syzbot]

Hello,

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

Reported-by: syzbot+2313dd...@syzkaller.appspotmail.com
Tested-by: syzbot+2313dd...@syzkaller.appspotmail.com

Tested on:

commit: 50760016 Merge tag 'loongarch-fixes-6.13-1' of git://g..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=17037c0f980000

kernel config: https://syzkaller.appspot.com/x/.config?x=50c7a61469ce77e7
dashboard link: https://syzkaller.appspot.com/bug?extid=2313dda4dc4885c93578
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=106c68f8580000

[syzbot]

Hello,

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

Reported-by: syzbot+2313dd...@syzkaller.appspotmail.com
Tested-by: syzbot+2313dd...@syzkaller.appspotmail.com

Tested on:

commit: 7cb1b466 Merge tag 'locking_urgent_for_v6.13_rc3' of g..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=138953e8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fee25f93665c89ac

dashboard link: https://syzkaller.appspot.com/bug?extid=2313dda4dc4885c93578
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=150153e8580000