From: Jan Kara <jack@xxxxxxx> commit 46c116b920ebec58031f0a78c5ea9599b0d2a371 upstream. 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@xxxxxxxxxxxxxxx Signed-off-by: Jan Kara <jack@xxxxxxx> Link: https://lore.kernel.org/r/20220518093332.13986-1-jack@xxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/namei.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -273,9 +273,9 @@ static struct dx_frame *dx_probe(struct 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(char *from, char *to, struct dx_map_entry *offsets, int count, unsigned blocksize); @@ -1205,15 +1205,23 @@ static inline int search_dirblock(struct * 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) { ext4fs_dirhash(dir, de->name, de->name_len, &h); map_tail--; @@ -1223,8 +1231,7 @@ static int dx_make_map(struct inode *dir 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; } @@ -1848,8 +1855,11 @@ static struct ext4_dir_entry_2 *do_split /* 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 */
