in ext4fs_read_file, it is possible for a broken/malicious file system to cause a memcpy of a negative number of bytes, which overflows all memory. This patch fixes the issue by checking for a negative length.
Signed-off-by: Paul Emge paulemge@forallsecure.com --- fs/ext4/ext4fs.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c index 85dc122f30..e2b740cac4 100644 --- a/fs/ext4/ext4fs.c +++ b/fs/ext4/ext4fs.c @@ -66,13 +66,15 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
ext_cache_init(&cache);
- if (blocksize <= 0) - return -1; - /* Adjust len so it we can't read past the end of the file. */ if (len + pos > filesize) len = (filesize - pos);
+ if (blocksize <= 0 || len <= 0) { + ext_cache_fini(&cache); + return -1; + } + blockcnt = lldiv(((len + pos) + blocksize - 1), blocksize);
for (i = lldiv(pos, blocksize); i < blockcnt; i++) {