From bb3d132a24cd8bf5e7773b2d9f9baa58b07a7dae Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Mon, 28 May 2012 14:16:57 -0400 Subject: [PATCH] ext4: fix potential NULL dereference in ext4_free_inodes_counts() The ext4_get_group_desc() function returns NULL on error, and ext4_free_inodes_count() function dereferences it without checking. There is a check on the next line, but it's too late. Reviewed-by: Jan Kara Signed-off-by: Dan Carpenter Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/ialloc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index a044a9b77491..ea32d7e1d6e3 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -508,10 +508,12 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, for (i = 0; i < ngroups; i++) { grp = (parent_group + i) % ngroups; desc = ext4_get_group_desc(sb, grp, NULL); - grp_free = ext4_free_inodes_count(sb, desc); - if (desc && grp_free && grp_free >= avefreei) { - *group = grp; - return 0; + if (desc) { + grp_free = ext4_free_inodes_count(sb, desc); + if (grp_free && grp_free >= avefreei) { + *group = grp; + return 0; + } } }