diff mbox series

[1/2] ext4: Verify dir block before splitting it

Message ID 20220428183143.5439-1-jack@suse.cz
State Accepted
Commit 46c116b920ebec58031f0a78c5ea9599b0d2a371
Headers show
Series [1/2] ext4: Verify dir block before splitting it | expand

Commit Message

Jan Kara April 28, 2022, 6:31 p.m. UTC 
Before splitting a directory block verify its directory entries are sane
so that the splitting code does not access memory it should not.

CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/namei.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

Comments

Jan Kara May 18, 2022, 9:09 a.m. UTC | #1 
On Tue 17-05-22 19:40:11, Theodore Ts'o wrote:
> On Thu, Apr 28, 2022 at 08:31:37PM +0200, Jan Kara wrote:
> > Before splitting a directory block verify its directory entries are sane
> > so that the splitting code does not access memory it should not.
> 
> This commit fails to build due to an undefined variable.  It's fixed
> with this hunk in the next patch, which needs to be brought back into
> this commit:
> 
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 5951e9bb348e..7286472e9558 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -1278,7 +1278,7 @@ static int dx_make_map(struct inode *dir, struct buffer_head *bh,
>  			count++;
>  			cond_resched();
>  		}
> -		de = ext4_next_entry(de, blocksize);
> +		de = ext4_next_entry(de, dir->i_sb->s_blocksize);
>  	}
>  	return count;
>  }
> 
> I was thinking about folding in this change and apply the patch with
> that change --- and I may yet do that --- but it looks like there's a
> bigger problem with this patch series, which is that it's causing a
> crash when running ext4/052 due to what appears to be a smashed stack.
> More about that in the reply to patch 2/2 of this series....

Yup, I'll fix that. Thanks for catching this.

								Honza
diff mbox series

Patch

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 767b4bfe39c3..ca6ee9940599 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -277,9 +277,9 @@  static struct dx_frame *dx_probe(struct ext4_filename *fname,
 				 struct dx_hash_info *hinfo,
 				 struct dx_frame *frame);
 static void dx_release(struct dx_frame *frames);
-static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
-		       unsigned blocksize, struct dx_hash_info *hinfo,
-		       struct dx_map_entry map[]);
+static int dx_make_map(struct inode *dir, struct buffer_head *bh,
+		       struct dx_hash_info *hinfo,
+		       struct dx_map_entry *map_tail);
 static void dx_sort_map(struct dx_map_entry *map, unsigned count);
 static struct ext4_dir_entry_2 *dx_move_dirents(struct inode *dir, char *from,
 					char *to, struct dx_map_entry *offsets,
@@ -1249,15 +1249,23 @@  static inline int search_dirblock(struct buffer_head *bh,
  * Create map of hash values, offsets, and sizes, stored at end of block.
  * Returns number of entries mapped.
  */
-static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
-		       unsigned blocksize, struct dx_hash_info *hinfo,
+static int dx_make_map(struct inode *dir, struct buffer_head *bh,
+		       struct dx_hash_info *hinfo,
 		       struct dx_map_entry *map_tail)
 {
 	int count = 0;
-	char *base = (char *) de;
+	struct ext4_dir_entry_2 *de = (struct ext4_dir_entry_2 *)bh->b_data;
+	unsigned int buflen = bh->b_size;
+	char *base = bh->b_data;
 	struct dx_hash_info h = *hinfo;
 
-	while ((char *) de < base + blocksize) {
+	if (ext4_has_metadata_csum(dir->i_sb))
+		buflen -= sizeof(struct ext4_dir_entry_tail);
+
+	while ((char *) de < base + buflen) {
+		if (ext4_check_dir_entry(dir, NULL, de, bh, base, buflen,
+					 ((char *)de) - base))
+			return -EFSCORRUPTED;
 		if (de->name_len && de->inode) {
 			if (ext4_hash_in_dirent(dir))
 				h.hash = EXT4_DIRENT_HASH(de);
@@ -1270,7 +1278,6 @@  static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
 			count++;
 			cond_resched();
 		}
-		/* XXX: do we need to check rec_len == 0 case? -Chris */
 		de = ext4_next_entry(de, blocksize);
 	}
 	return count;
@@ -1943,8 +1950,11 @@  static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 
 	/* create map in the end of data2 block */
 	map = (struct dx_map_entry *) (data2 + blocksize);
-	count = dx_make_map(dir, (struct ext4_dir_entry_2 *) data1,
-			     blocksize, hinfo, map);
+	count = dx_make_map(dir, *bh, hinfo, map);
+	if (count < 0) {
+		err = count;
+		goto journal_error;
+	}
 	map -= count;
 	dx_sort_map(map, count);
 	/* Ensure that neither split block is over half full */