| From b19b68fd05ef68b11ac3e5f4336bb1a2ec9d791c Mon Sep 17 00:00:00 2001 |
| From: Brian Foster <bfoster@redhat.com> |
| Date: Tue, 3 Dec 2019 07:53:15 -0800 |
| Subject: [PATCH] xfs: fix mount failure crash on invalid iclog memory access |
| |
| commit 798a9cada4694ca8d970259f216cec47e675bfd5 upstream. |
| |
| 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 <bfoster@redhat.com> |
| Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> |
| Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c |
| index 2466b0f5b6c4..80c4b21988df 100644 |
| --- a/fs/xfs/xfs_log.c |
| +++ b/fs/xfs/xfs_log.c |
| @@ -1579,6 +1579,8 @@ 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); |
| -- |
| 2.7.4 |
| |
