From e1a4d74154ba71c8d2edd391b4696852db6b9c0d Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Tue, 3 Dec 2019 07:53:15 -0800 Subject: [PATCH] xfs: fix mount failure crash on invalid iclog memory access task #28557760 [ Upstream commit 798a9cada4694ca8d970259f216cec47e675bfd5 ] syzbot (via KASAN) reports a use-after-free in the error path of xlog_alloc_log(). Specifically, the iclog freeing loop doesn't handle the case of a fully initialized ->l_iclog linked list. Instead, it assumes that the list is partially constructed and NULL terminated. This bug manifested because there was no possible error scenario after iclog list setup when the original code was added. Subsequent code and associated error conditions were added some time later, while the original error handling code was never updated. Fix up the error loop to terminate either on a NULL iclog or reaching the end of the list. Reported-by: syzbot+c732f8644185de340492@syzkaller.appspotmail.com Signed-off-by: Brian Foster Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Sasha Levin Signed-off-by: Jeffle Xu Acked-by: Joseph Qi --- fs/xfs/xfs_log.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index ffdc3f58867e..ce1b8400cff9 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1575,6 +1575,8 @@ xlog_alloc_log( if (iclog->ic_bp) xfs_buf_free(iclog->ic_bp); kmem_free(iclog); + if (prev_iclog == log->l_iclog) + break; } spinlock_destroy(&log->l_icloglock); xfs_buf_free(log->l_xbuf); -- GitLab