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 | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 767b4bfe39c3..2a55f23e4524 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); @@ -1270,8 +1278,7 @@ 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); + de = ext4_next_entry(de, dir->i_sb->s_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 */