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authorTheodore Ts'o <tytso@mit.edu>2009-04-22 20:52:25 -0400
committerTheodore Ts'o <tytso@mit.edu>2009-04-22 20:52:25 -0400
commite84a26ce178345498a7eca0590852bcc36f1092f (patch)
treedcd2f95c9f73ffb8d2020fe89bb1c30785e0fa78
parent38d726d153cfe5efe5fe22d28d36ab382dda3a5c (diff)
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" <tytso@mit.edu>
-rw-r--r--fs/ext4/extents.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 6132353dcf6..c28ffe25950 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;