reiserfs: possible null pointer dereference during resize

sb_read may return NULL, let's explicitly check it.  If so free new bitmap
blocks array, after this we may safely exit as it done above during bitmap
allocation.

Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/reiserfs/resize.c b/fs/reiserfs/resize.c
index 315684793d1d..976cc7887a0d 100644
--- a/fs/reiserfs/resize.c
+++ b/fs/reiserfs/resize.c
@@ -131,6 +131,10 @@ int reiserfs_resize(struct super_block *s, unsigned long block_count_new)
                         /* don't use read_bitmap_block since it will cache
                          * the uninitialized bitmap */
                         bh = sb_bread(s, i * s->s_blocksize * 8);
+                        if (!bh) {
+                                vfree(bitmap);
+                                return -EIO;
+                        }
                         memset(bh->b_data, 0, sb_blocksize(sb));
                         reiserfs_test_and_set_le_bit(0, bh->b_data);
                         reiserfs_cache_bitmap_metadata(s, bh, bitmap + i);