Commit 353ebd3e authored by Theodore Ts'o's avatar Theodore Ts'o Committed by Greg Kroah-Hartman

ext4: verify the depth of extent tree in ext4_find_extent()

commit bc890a60 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=199417Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent db3b00e3
......@@ -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) + \
......
......@@ -876,6 +876,12 @@ 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 = -EFSCORRUPTED;
goto err;
}
if (path) {
ext4_ext_drop_refs(path);
......
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