[PATCH] Test for sb_getblk return value

This patch adds tests for the return value of sb_getblk() in the ext2/3
filesystems.  In fs/buffer.c it is stated that the getblk() function never
fails.  However, it does can return NULL in some situations due to I/O
errors, which may lead us to NULL pointer dereferences

Signed-off-by: Glauber de Oliveira Costa <glommer@br.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index fdba4d1d3c6..e7d3f0522d0 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -440,6 +440,10 @@ static int ext2_alloc_branch(struct inode *inode,
                  * the pointer to new one, then send parent to disk.
                  */
                 bh = sb_getblk(inode->i_sb, parent);
+                if (!bh) {
+                        err = -EIO;
+                        break;
+                }
                 lock_buffer(bh);
                 memset(bh->b_data, 0, blocksize);
                 branch[n].bh = bh;