4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Eric Biggers <[email protected]> commit ce3fd194fcc6fbdc00ce095a852f22df97baa401 upstream. ext4 isn't validating the sizes of xattrs where the value of the xattr is stored in an external inode. This is problematic because ->e_value_size is a u32, but ext4_xattr_get() returns an int. A very large size is misinterpreted as an error code, which ext4_get_acl() translates into a bogus ERR_PTR() for which IS_ERR() returns false, causing a crash. Fix this by validating that all xattrs are <= INT_MAX bytes. This issue has been assigned CVE-2018-1095. https://bugzilla.kernel.org/show_bug.cgi?id=199185 https://bugzilla.redhat.com/show_bug.cgi?id=1560793 Reported-by: Wen Xu <[email protected]> Signed-off-by: Eric Biggers <[email protected]> Signed-off-by: Theodore Ts'o <[email protected]> Cc: [email protected] Fixes: e50e5129f384 ("ext4: xattr-in-inode support") Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/ext4/xattr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -194,10 +194,13 @@ ext4_xattr_check_entries(struct ext4_xat /* Check the values */ while (!IS_LAST_ENTRY(entry)) { - if (entry->e_value_size != 0 && - entry->e_value_inum == 0) { + u32 size = le32_to_cpu(entry->e_value_size); + + if (size > INT_MAX) + return -EFSCORRUPTED; + + if (size != 0 && entry->e_value_inum == 0) { u16 offs = le16_to_cpu(entry->e_value_offs); - u32 size = le32_to_cpu(entry->e_value_size); void *value; /*
