From 4ac577ae741e745ecfb64c5a9c7f52fc36aca022 Mon Sep 17 00:00:00 2001 From: Edward Adam Davis Date: Thu, 27 Nov 2025 11:26:40 +0800 Subject: [PATCH] ocfs2: check tl_used after reading it from trancate log inode The fuzz image has a truncate log inode whose tl_used is bigger than tl_count so it triggers the BUG in ocfs2_truncate_log_needs_flush() [1]. As what the check in ocfs2_truncate_log_needs_flush() does, just do same check into ocfs2_get_truncate_log_info() when truncate log inode is reading in so we can bail out earlier. [1] (syz.0.17,5491,0):ocfs2_truncate_log_needs_flush:5830 ERROR: bug expression: le16_to_cpu(tl->tl_used) > le16_to_cpu(tl->tl_count) kernel BUG at fs/ocfs2/alloc.c:5830! RIP: 0010:ocfs2_truncate_log_needs_flush fs/ocfs2/alloc.c:5827 [inline] Call Trace: ocfs2_commit_truncate+0xb64/0x21d0 fs/ocfs2/alloc.c:7372 ocfs2_truncate_file+0xca2/0x1420 fs/ocfs2/file.c:509 ocfs2_setattr+0x1520/0x1b40 fs/ocfs2/file.c:1212 notify_change+0xc1a/0xf40 fs/attr.c:546 do_truncate+0x1a4/0x220 fs/open.c:68 Link: https://lkml.kernel.org/r/tencent_B24B1C1BE225DCBA44BB6933AB9E1B1B0708@qq.com Reported-by: syzbot+f82afc4d4e74d0ef7a89@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f82afc4d4e74d0ef7a89 Tested-by: syzbot+f82afc4d4e74d0ef7a89@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis Reviewed-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Signed-off-by: Andrew Morton --- fs/ocfs2/alloc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c index 162711cc5b20..ba26d21344bd 100644 --- a/fs/ocfs2/alloc.c +++ b/fs/ocfs2/alloc.c @@ -6164,7 +6164,7 @@ static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb, struct buffer_head *bh = NULL; struct ocfs2_dinode *di; struct ocfs2_truncate_log *tl; - unsigned int tl_count; + unsigned int tl_count, tl_used; inode = ocfs2_get_system_file_inode(osb, TRUNCATE_LOG_SYSTEM_INODE, @@ -6185,8 +6185,10 @@ static int ocfs2_get_truncate_log_info(struct ocfs2_super *osb, di = (struct ocfs2_dinode *)bh->b_data; tl = &di->id2.i_dealloc; tl_count = le16_to_cpu(tl->tl_count); + tl_used = le16_to_cpu(tl->tl_used); if (unlikely(tl_count > ocfs2_truncate_recs_per_inode(osb->sb) || - tl_count == 0)) { + tl_count == 0 || + tl_used > tl_count)) { status = -EFSCORRUPTED; iput(inode); brelse(bh); -- 2.47.3