ext4: handle NULL p_ext in ext4_ext_next_allocated_block()
authorCurt Wohlgemuth <curtw@google.com>
Wed, 26 Oct 2011 08:38:59 +0000 (04:38 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Wed, 26 Oct 2011 08:38:59 +0000 (04:38 -0400)
commit6f8ff537266ee5396c920fb0c842a21df3055ff3
treea024979a4e8f718289e9bf36fc165b96b68d6209
parentf85b287a01237857a50c93868231f7e831581a27
ext4: handle NULL p_ext in ext4_ext_next_allocated_block()

In ext4_ext_next_allocated_block(), the path[depth] might
have a p_ext that is NULL -- see ext4_ext_binsearch().  In
such a case, dereferencing it will crash the machine.

This patch checks for p_ext == NULL in
ext4_ext_next_allocated_block() before dereferencinging it.

Tested using a hand-crafted an inode with eh_entries == 0 in
an extent block, verified that running FIEMAP on it crashes
without this patch, works fine with it.

Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
fs/ext4/extents.c