4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Torvalds torvalds@linux-foundation.org
commit 01cfb7937a9af2abb1136c7e89fbf3fd92952956 upstream.
Anatoly Trosinenko reports that a corrupted squashfs image can cause a kernel oops. It turns out that squashfs can end up being confused about negative fragment lengths.
The regular squashfs_read_data() does check for negative lengths, but squashfs_read_metadata() did not, and the fragment size code just blindly trusted the on-disk value. Fix both the fragment parsing and the metadata reading code.
Reported-by: Anatoly Trosinenko anatoly.trosinenko@gmail.com Cc: Al Viro viro@zeniv.linux.org.uk Cc: Phillip Lougher phillip@squashfs.org.uk Cc: stable@kernel.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/squashfs/cache.c | 3 +++ fs/squashfs/file.c | 8 ++++++-- fs/squashfs/fragment.c | 4 +--- fs/squashfs/squashfs_fs.h | 6 ++++++ 4 files changed, 16 insertions(+), 5 deletions(-)
--- a/fs/squashfs/cache.c +++ b/fs/squashfs/cache.c @@ -350,6 +350,9 @@ int squashfs_read_metadata(struct super_
TRACE("Entered squashfs_read_metadata [%llx:%x]\n", *block, *offset);
+ if (unlikely(length < 0)) + return -EIO; + while (length) { entry = squashfs_cache_get(sb, msblk->block_cache, *block, 0); if (entry->error) { --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -194,7 +194,11 @@ static long long read_indexes(struct sup }
for (i = 0; i < blocks; i++) { - int size = le32_to_cpu(blist[i]); + int size = squashfs_block_size(blist[i]); + if (size < 0) { + err = size; + goto failure; + } block += SQUASHFS_COMPRESSED_SIZE_BLOCK(size); } n -= blocks; @@ -367,7 +371,7 @@ static int read_blocklist(struct inode * sizeof(size)); if (res < 0) return res; - return le32_to_cpu(size); + return squashfs_block_size(size); }
/* Copy data into page cache */ --- a/fs/squashfs/fragment.c +++ b/fs/squashfs/fragment.c @@ -61,9 +61,7 @@ int squashfs_frag_lookup(struct super_bl return size;
*fragment_block = le64_to_cpu(fragment_entry.start_block); - size = le32_to_cpu(fragment_entry.size); - - return size; + return squashfs_block_size(fragment_entry.size); }
--- a/fs/squashfs/squashfs_fs.h +++ b/fs/squashfs/squashfs_fs.h @@ -129,6 +129,12 @@
#define SQUASHFS_COMPRESSED_BLOCK(B) (!((B) & SQUASHFS_COMPRESSED_BIT_BLOCK))
+static inline int squashfs_block_size(__le32 raw) +{ + u32 size = le32_to_cpu(raw); + return (size >> 25) ? -EIO : size; +} + /* * Inode number ops. Inodes consist of a compressed block number, and an * uncompressed offset within that block