From 56b19868aca856a7d7bf20c3a7a1030e4fd75b2b Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Thu, 12 Mar 2009 09:51:20 -0400 Subject: ext4: Add checks to validate extent entries. This patch adds checks to validate the extent entries along with extent headers, to avoid crashes caused by corrupt filesystems. Signed-off-by: Aneesh Kumar K.V Signed-off-by: "Theodore Ts'o" --- fs/ext4/extents.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 71 insertions(+), 10 deletions(-) (limited to 'fs') diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index aa3431856c9..ee40b7c52c8 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -324,7 +324,64 @@ ext4_ext_max_entries(struct inode *inode, int depth) return max; } -static int __ext4_ext_check_header(const char *function, struct inode *inode, +static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext) +{ + ext4_fsblk_t block = ext_pblock(ext); + 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)))) + return 0; + else + return 1; +} + +static int ext4_valid_extent_idx(struct inode *inode, + struct ext4_extent_idx *ext_idx) +{ + ext4_fsblk_t block = idx_pblock(ext_idx); + 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)))) + return 0; + else + return 1; +} + +static int ext4_valid_extent_entries(struct inode *inode, + struct ext4_extent_header *eh, + int depth) +{ + struct ext4_extent *ext; + struct ext4_extent_idx *ext_idx; + unsigned short entries; + if (eh->eh_entries == 0) + return 1; + + entries = le16_to_cpu(eh->eh_entries); + + if (depth == 0) { + /* leaf entries */ + ext = EXT_FIRST_EXTENT(eh); + while (entries) { + if (!ext4_valid_extent(inode, ext)) + return 0; + ext++; + entries--; + } + } else { + ext_idx = EXT_FIRST_INDEX(eh); + while (entries) { + if (!ext4_valid_extent_idx(inode, ext_idx)) + return 0; + ext_idx++; + entries--; + } + } + return 1; +} + +static int __ext4_ext_check(const char *function, struct inode *inode, struct ext4_extent_header *eh, int depth) { @@ -352,11 +409,15 @@ static int __ext4_ext_check_header(const char *function, struct inode *inode, error_msg = "invalid eh_entries"; goto corrupted; } + if (!ext4_valid_extent_entries(inode, eh, depth)) { + error_msg = "invalid extent entries"; + goto corrupted; + } return 0; corrupted: ext4_error(inode->i_sb, function, - "bad header in inode #%lu: %s - magic %x, " + "bad header/extent in inode #%lu: %s - magic %x, " "entries %u, max %u(%u), depth %u(%u)", inode->i_ino, error_msg, le16_to_cpu(eh->eh_magic), le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max), @@ -365,8 +426,8 @@ corrupted: return -EIO; } -#define ext4_ext_check_header(inode, eh, depth) \ - __ext4_ext_check_header(__func__, inode, eh, depth) +#define ext4_ext_check(inode, eh, depth) \ + __ext4_ext_check(__func__, inode, eh, depth) #ifdef EXT_DEBUG static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path) @@ -570,7 +631,7 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block, eh = ext_inode_hdr(inode); depth = ext_depth(inode); - if (ext4_ext_check_header(inode, eh, depth)) + if (ext4_ext_check(inode, eh, depth)) return ERR_PTR(-EIO); @@ -607,7 +668,7 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block, path[ppos].p_hdr = eh; i--; - if (ext4_ext_check_header(inode, eh, i)) + if (ext4_ext_check(inode, eh, i)) goto err; } @@ -1204,7 +1265,7 @@ got_index: return -EIO; eh = ext_block_hdr(bh); /* subtract from p_depth to get proper eh_depth */ - if (ext4_ext_check_header(inode, eh, path->p_depth - depth)) { + if (ext4_ext_check(inode, eh, path->p_depth - depth)) { put_bh(bh); return -EIO; } @@ -1217,7 +1278,7 @@ got_index: if (bh == NULL) return -EIO; eh = ext_block_hdr(bh); - if (ext4_ext_check_header(inode, eh, path->p_depth - depth)) { + if (ext4_ext_check(inode, eh, path->p_depth - depth)) { put_bh(bh); return -EIO; } @@ -2160,7 +2221,7 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start) return -ENOMEM; } path[0].p_hdr = ext_inode_hdr(inode); - if (ext4_ext_check_header(inode, path[0].p_hdr, depth)) { + if (ext4_ext_check(inode, path[0].p_hdr, depth)) { err = -EIO; goto out; } @@ -2214,7 +2275,7 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start) err = -EIO; break; } - if (ext4_ext_check_header(inode, ext_block_hdr(bh), + if (ext4_ext_check(inode, ext_block_hdr(bh), depth - i - 1)) { err = -EIO; break; -- cgit v1.2.3