ext4: always check ext4_ext_find_extent result
Where are some places where logic guaranties us that extent we are
searching exits, but this may not be true due to on-disk data
corruption. If such corruption happens we must prevent possible
null pointer dereferences.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 38be063..64b4003 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3313,6 +3313,11 @@
return PTR_ERR(path);
depth = ext_depth(inode);
ex = path[depth].p_ext;
+ if (!ex) {
+ EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+ (unsigned long) map->m_lblk);
+ return -EIO;
+ }
uninitialized = ext4_ext_is_uninitialized(ex);
split_flag1 = 0;
@@ -3694,6 +3699,12 @@
}
depth = ext_depth(inode);
ex = path[depth].p_ext;
+ if (!ex) {
+ EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+ (unsigned long) map->m_lblk);
+ err = -EIO;
+ goto out;
+ }
}
err = ext4_ext_get_access(handle, inode, path + depth);
@@ -5340,6 +5351,12 @@
return PTR_ERR(path);
depth = path->p_depth;
extent = path[depth].p_ext;
+ if (!extent) {
+ EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+ (unsigned long) start);
+ return -EIO;
+ }
+
current_block = le32_to_cpu(extent->ee_block);
if (start > current_block) {
/* Hole, move to the next extent */