From e84a26ce178345498a7eca0590852bcc36f1092f Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Wed, 22 Apr 2009 20:52:25 -0400 Subject: [PATCH] ext4: Make the extent validity check more paranoid Instead of just checking that the extent block number is greater or equal than s_first_data_block, make sure it it is not pointing into the block group descriptors, since that is clearly wrong. This helps prevent filesystem from getting very badly corrupted in case an extent block is corrupted. Signed-off-by: "Theodore Ts'o" --- fs/ext4/extents.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 6132353dcf62..c28ffe259506 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -326,11 +326,14 @@ ext4_ext_max_entries(struct inode *inode, int depth) static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext) { - ext4_fsblk_t block = ext_pblock(ext); + ext4_fsblk_t block = ext_pblock(ext), valid_block; int len = ext4_ext_get_actual_len(ext); struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; - if (unlikely(block < le32_to_cpu(es->s_first_data_block) || - ((block + len) > ext4_blocks_count(es)))) + + valid_block = le32_to_cpu(es->s_first_data_block) + + EXT4_SB(inode->i_sb)->s_gdb_count; + if (unlikely(block <= valid_block || + ((block + len) > ext4_blocks_count(es)))) return 0; else return 1; @@ -339,10 +342,13 @@ static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext) static int ext4_valid_extent_idx(struct inode *inode, struct ext4_extent_idx *ext_idx) { - ext4_fsblk_t block = idx_pblock(ext_idx); + ext4_fsblk_t block = idx_pblock(ext_idx), valid_block; struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; - if (unlikely(block < le32_to_cpu(es->s_first_data_block) || - (block >= ext4_blocks_count(es)))) + + valid_block = le32_to_cpu(es->s_first_data_block) + + EXT4_SB(inode->i_sb)->s_gdb_count; + if (unlikely(block <= valid_block || + (block >= ext4_blocks_count(es)))) return 0; else return 1; -- 2.20.1