With i_extra_isize equal to or close to the available space, it was
possible for us to read past the end of the inode when trying to detect
or validate in-inode xattrs. Fix this by checking for the needed extra
space first.
This patch shouldn't have any noticeable effect on
non-corrupted/non-malicious filesystems.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/ext4/inode.c | 4 +++-
fs/ext4/xattr.c | 5 ++---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bc99ebe..e52f41a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4519,7 +4519,9 @@ static inline void ext4_iget_extra_inode(struct inode *inode,
{
__le32 *magic = (void *)raw_inode +
EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
- if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
+ if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32)
+ <= EXT4_INODE_SIZE(inode->i_sb) &&
+ *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
ext4_set_inode_state(inode, EXT4_STATE_XATTR);
ext4_find_inline_data_nolock(inode);
} else
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 1846e91..59c9ec7 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -231,13 +231,12 @@ static int
__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
void *end, const char *function, unsigned int line)
{
- struct ext4_xattr_entry *entry = IFIRST(header);
int error = -EFSCORRUPTED;
- if (((void *) header >= end) ||
+ if (end - (void *)header < sizeof(*header) + sizeof(u32) ||
(header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))
goto errout;
- error = ext4_xattr_check_names(entry, end, entry);
+ error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
errout:
if (error)
__ext4_error_inode(inode, function, line, 0,
--
2.8.0.rc3.226.g39d4020
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