[PATCH 1/3] ext4: Fix error handling in ext4_ext_shift_extents

[PATCH 1/3] ext4: Fix error handling in ext4_ext_shift_extents

[Dmitry Monakhov]

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/ext4/extents.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 96e0a4b..38be063 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5314,11 +5314,18 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 	 * enough to accomodate the shift.
 	 */
 	path = ext4_ext_find_extent(inode, start - 1, NULL, 0);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
 	depth = path->p_depth;
 	extent =  path[depth].p_ext;
-	ex_start = le32_to_cpu(extent->ee_block);
-	ex_end = le32_to_cpu(extent->ee_block) +
+	if (extent) {
+		ex_start = le32_to_cpu(extent->ee_block);
+		ex_end = le32_to_cpu(extent->ee_block) +
 			ext4_ext_get_actual_len(extent);
+	} else {
+		ex_start = 0;
+		ex_end = 0;
+	}
 	ext4_ext_drop_refs(path);
 	kfree(path);
 
-- 
1.7.1

[PATCH 2/3] ext4: always check ext4_ext_find_extent result

[Dmitry Monakhov]

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>
---
 fs/ext4/extents.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 38be063..f20effb 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3313,6 +3313,10 @@ static int ext4_split_extent(handle_t *handle,
 		return PTR_ERR(path);
 	depth = ext_depth(inode);
 	ex = path[depth].p_ext;
+	if (!ex) {
+		EXT4_ERROR_INODE(inode, "unexpected hole at %lu", map->m_lblk);
+		return -EIO;
+	}
 	uninitialized = ext4_ext_is_uninitialized(ex);
 	split_flag1 = 0;
 
@@ -3694,6 +3698,12 @@ static int ext4_convert_initialized_extents(handle_t *handle,
 		}
 		depth = ext_depth(inode);
 		ex = path[depth].p_ext;
+		if (!ex) {
+			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+					 map->m_lblk);
+			err = -EIO;
+			goto out;
+		}
 	}
 
 	err = ext4_ext_get_access(handle, inode, path + depth);
@@ -5340,6 +5350,12 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 			return PTR_ERR(path);
 		depth = path->p_depth;
 		extent = path[depth].p_ext;
+		if (!extent) {
+			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+					 start);
+			return -EIO;
+		}
+
 		current_block = le32_to_cpu(extent->ee_block);
 		if (start > current_block) {
 			/* Hole, move to the next extent */
-- 
1.7.1

Re: [PATCH 2/3] ext4: always check ext4_ext_find_extent result

[Theodore Ts'o]

On Sun, Apr 13, 2014 at 07:36:00PM +0400, Dmitry Monakhov wrote:
> 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>

Thanks, applied.

					- Ted

[PATCH 3/3] ext4: remove obsoleted check

[Dmitry Monakhov]

BH can not be NULL at this point, ext4_read_dirblock() always return
non null value, and we already have done all necessery checks.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/ext4/namei.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 1cb84f7..a683f95 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2510,8 +2510,7 @@ static int empty_dir(struct inode *inode)
 		 ext4_rec_len_from_disk(de1->rec_len, sb->s_blocksize);
 	de = ext4_next_entry(de1, sb->s_blocksize);
 	while (offset < inode->i_size) {
-		if (!bh ||
-		    (void *) de >= (void *) (bh->b_data+sb->s_blocksize)) {
+		if ((void *) de >= (void *) (bh->b_data+sb->s_blocksize)) {
 			unsigned int lblock;
 			err = 0;
 			brelse(bh);
-- 
1.7.1

Re: [PATCH 3/3] ext4: remove obsoleted check

[Theodore Ts'o]

On Sun, Apr 13, 2014 at 07:36:01PM +0400, Dmitry Monakhov wrote:
> BH can not be NULL at this point, ext4_read_dirblock() always return
> non null value, and we already have done all necessery checks.
> 
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>

Thanks, queued for the next merge window (since it's not a bug fix,
but just a clean up).

						- Ted

Re: [PATCH 1/3] ext4: Fix error handling in ext4_ext_shift_extents

[Theodore Ts'o]

On Sun, Apr 13, 2014 at 07:35:59PM +0400, Dmitry Monakhov wrote:
> 
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>

Thanks, applied (and will be pushed as part of bug fixes for 3.15).

		     	     	    - Ted