diff options
author | Theodore Ts'o <tytso@mit.edu> | 2018-06-14 12:55:10 -0400 |
---|---|---|
committer | Todd Kjos <tkjos@google.com> | 2019-01-04 09:40:44 -0800 |
commit | 96320f8117315463276f48dfe362ea42d4b771e9 (patch) | |
tree | 041ef5051770c8f6e9803c2ad8a1b86716dacc0f | |
parent | bd1546f858dc0ddc659fd3d645009245638b7b73 (diff) |
ext4: verify the depth of extent tree in ext4_find_extent()ASB-2019-01-05_3.18-o-mr1
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>
[bwh: Backported to 3.16: return -EIO instead of -EFSCORRUPTED]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | fs/ext4/ext4_extents.h | 1 | ||||
-rw-r--r-- | fs/ext4/extents.c | 6 |
2 files changed, 7 insertions, 0 deletions
diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h index 3c9381547094..2d8e73793512 100644 --- 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) + \ diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 9e2363b2c372..0e9e8ab0255d 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -870,6 +870,12 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block, 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 = -EIO; + goto err; + } if (path) { ext4_ext_drop_refs(path); |