| From bc890a60247171294acc0bd67d211fa4b88d40ba Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| Date: Thu, 14 Jun 2018 12:55:10 -0400 |
| Subject: ext4: verify the depth of extent tree in ext4_find_extent() |
| |
| From: Theodore Ts'o <tytso@mit.edu> |
| |
| commit bc890a60247171294acc0bd67d211fa4b88d40ba upstream. |
| |
| If there is a corupted file system where the claimed depth of the |
| extent tree is -1, this can cause a massive buffer overrun leading to |
| sadness. |
| |
| This addresses CVE-2018-10877. |
| |
| https://bugzilla.kernel.org/show_bug.cgi?id=199417 |
| |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Cc: stable@kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/ext4_extents.h | 1 + |
| fs/ext4/extents.c | 6 ++++++ |
| 2 files changed, 7 insertions(+) |
| |
| --- a/fs/ext4/ext4_extents.h |
| +++ b/fs/ext4/ext4_extents.h |
| @@ -103,6 +103,7 @@ struct ext4_extent_header { |
| }; |
| |
| #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) |
| +#define EXT4_MAX_EXTENT_DEPTH 5 |
| |
| #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ |
| (sizeof(struct ext4_extent_header) + \ |
| --- a/fs/ext4/extents.c |
| +++ b/fs/ext4/extents.c |
| @@ -876,6 +876,12 @@ ext4_find_extent(struct inode *inode, ex |
| |
| eh = ext_inode_hdr(inode); |
| depth = ext_depth(inode); |
| + if (depth < 0 || depth > EXT4_MAX_EXTENT_DEPTH) { |
| + EXT4_ERROR_INODE(inode, "inode has invalid extent depth: %d", |
| + depth); |
| + ret = -EFSCORRUPTED; |
| + goto err; |
| + } |
| |
| if (path) { |
| ext4_ext_drop_refs(path); |