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ext4: always check ext4_ext_find_extent result 

Where are some places where logic guaranties us that extent we are
searching exits, but this may not be true due to on-disk data
corruption. If such corruption happens we must prevent possible
null pointer dereferences.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Dmitry Monakhov 2014-04-13 15:41:13 -04:00 committed by Theodore Ts'o
parent 8dc79ec4c0
commit a18ed359bd
1 changed files with 17 additions and 0 deletions
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17
fs/ext4/extents.c
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@ -3313,6 +3313,11 @@ static int ext4_split_extent(handle_t *handle,
return PTR_ERR(path); return PTR_ERR(path);
depth = ext_depth(inode); depth = ext_depth(inode);
ex = path[depth].p_ext; ex = path[depth].p_ext;
if (!ex) {
EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
(unsigned long) map->m_lblk);
return -EIO;
}
uninitialized = ext4_ext_is_uninitialized(ex); uninitialized = ext4_ext_is_uninitialized(ex);
split_flag1 = 0; split_flag1 = 0;
@ -3694,6 +3699,12 @@ static int ext4_convert_initialized_extents(handle_t *handle,
} }
depth = ext_depth(inode); depth = ext_depth(inode);
ex = path[depth].p_ext; ex = path[depth].p_ext;
if (!ex) {
EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
(unsigned long) map->m_lblk);
err = -EIO;
goto out;
}
} }
err = ext4_ext_get_access(handle, inode, path + depth); err = ext4_ext_get_access(handle, inode, path + depth);
@ -5340,6 +5351,12 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
return PTR_ERR(path); return PTR_ERR(path);
depth = path->p_depth; depth = path->p_depth;
extent = path[depth].p_ext; extent = path[depth].p_ext;
if (!extent) {
EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
(unsigned long) start);
return -EIO;
}
current_block = le32_to_cpu(extent->ee_block); current_block = le32_to_cpu(extent->ee_block);
if (start > current_block) { if (start > current_block) {
/* Hole, move to the next extent */ /* Hole, move to the next extent */