ocfs2: check tl->count of truncate log inode in ocfs2_get_truncate_log_info

syz reported:

(syz-executor404,5313,0):ocfs2_truncate_log_append:5874 ERROR: bug
expression: tl_count > ocfs2_truncate_recs_per_inode(osb->sb) ||
tl_count == 0
(syz-executor404,5313,0):ocfs2_truncate_log_append:5874 ERROR: Truncate
record count on torvalds#77 invalid wanted 39, actual 2087
------------[ cut here  ]------------
kernel BUG at fs/ocfs2/alloc.c:5874!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5313 Comm: syz-executor404 Not tainted
6.12.0-rc5-syzkaller-00299-g11066801dd4b #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:ocfs2_truncate_log_append+0x9a8/0x9c0 fs/ocfs2/alloc.c:5868
RSP: 0018:ffffc9000cf16f40 EFLAGS: 00010292
RAX: b4b54f1d10640800 RBX: 0000000000000027 RCX: b4b54f1d10640800
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000cf17070 R08: ffffffff8174a14c R09: 1ffff11003f8519a
R10: dffffc0000000000 R11: ffffed1003f8519b R12: 1ffff110085f5f58
R13: ffffff3800000000 R14: 000000000000004d R15: ffff8880438f0008
FS:  00005555722df380(0000) GS:ffff88801fc00000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000f000 CR3: 000000004010e000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ocfs2_remove_btree_range+0x1303/0x1860 fs/ocfs2/alloc.c:5789
ocfs2_remove_inode_range+0xff3/0x29f0 fs/ocfs2/file.c:1907
ocfs2_reflink_remap_extent fs/ocfs2/refcounttree.c:4537 [inline]
ocfs2_reflink_remap_blocks+0xcd4/0x1f30 fs/ocfs2/refcounttree.c:4684
ocfs2_remap_file_range+0x5fa/0x8d0 fs/ocfs2/file.c:2736
vfs_copy_file_range+0xc07/0x1510 fs/read_write.c:1615
__do_sys_copy_file_range fs/read_write.c:1705 [inline]
__se_sys_copy_file_range+0x3f2/0x5d0 fs/read_write.c:1668
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: 0033:0x7fd327167af9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 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:00007ffe6b8e22e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000146
RAX: ffffffffffffffda RBX: 00007fd3271b005e RCX: 00007fd327167af9
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fd3271de610 R08: 000000000000d8c2 R09: 0000000000000000
R10: 0000000020000640 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe6b8e24b8 R14: 0000000000000001 R15: 0000000000000001
</TASK>

The fuzz image has a truncate log inode whose tl_count is bigger than
ocfs2_truncate_recs_per_inode() so it triggers the BUG in
ocfs2_truncate_log_append().

As what the check in ocfs2_truncate_log_append() does, just do same check
into ocfs2_get_truncate_log_info when truncate log inode is reading in so
we can bail out earlier.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Su Yue <[email protected]>
Reported-by: Liebes Wang <[email protected]>
Link: https://lore.kernel.org/ocfs2-devel/CADCV8souQhdP0RdQF1U7KTWtuHDfpn+3LnTt-EEuMmB-pMRrgQ@mail.gmail.com/T/#u
Reported-by: [email protected]
Tested-by: [email protected]
Reviewed-by: Joseph Qi <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Changwei Ge <[email protected]>
Cc: Jun Piao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Damenly

fs/ocfs2/alloc.c

@@ -6154,6 +6154,9 @@ static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb,
 	int status;
 	struct inode *inode = NULL;
 	struct buffer_head *bh = NULL;
+	struct ocfs2_dinode *di;
+	struct ocfs2_truncate_log *tl;
+	unsigned int tl_count;
 
 	inode = ocfs2_get_system_file_inode(osb,
 					   TRUNCATE_LOG_SYSTEM_INODE,
@@ -6171,6 +6174,18 @@ static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb,
 		goto bail;
 	}
 
+	di = (struct ocfs2_dinode *)bh->b_data;
+	tl = &di->id2.i_dealloc;
+	tl_count = le16_to_cpu(tl->tl_count);
+	if (unlikely(tl_count > ocfs2_truncate_recs_per_inode(osb->sb) ||
+		     tl_count == 0)) {
+		status = -EFSCORRUPTED;
+		iput(inode);
+		brelse(bh);
+		mlog_errno(status);
+		goto bail;
+	}
+
 	*tl_inode = inode;
 	*tl_bh    = bh;
 bail: