From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Mon, 31 Jul 2017 20:08:13 +0000 (-0500)
Subject: xfs: check _alloc_read_agf buffer pointer before using
X-Git-Tag: v4.13.0-rc1~42
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d705962a19dc6b3e8db9530b6f7571ea0220682f;p=thirdparty%2Fxfsprogs-dev.git

xfs: check _alloc_read_agf buffer pointer before using

Source kernel commit: 10479e2dea83d4c421ad05dfc55d918aa8dfc0cd

In some circumstances, _alloc_read_agf can return an error code of zero
but also a null AGF buffer pointer.  Check for this and jump out.

Fixes-coverity-id: 1415250
Fixes-coverity-id: 1415320
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

diff --git a/libxfs/xfs_refcount.c b/libxfs/xfs_refcount.c
index 52ec20c74..3e0c81523 100644
--- a/libxfs/xfs_refcount.c
+++ b/libxfs/xfs_refcount.c
@@ -1637,6 +1637,10 @@ xfs_refcount_recover_cow_leftovers(
 	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
 	if (error)
 		goto out_trans;
+	if (!agbp) {
+		error = -ENOMEM;
+		goto out_trans;
+	}
 	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);
 
 	/* Find all the leftover CoW staging extents. */