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authorLinus Torvalds <torvalds@linux-foundation.org>2018-07-29 12:44:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-07-29 12:44:46 -0700
commit01cfb7937a9af2abb1136c7e89fbf3fd92952956 (patch)
tree2b01fbc7eb315150d5a0ed71a218e4008801138b
parenta26fb01c2879ed7026e6cbd78bb701912d249eef (diff)
download96b-common-01cfb7937a9af2abb1136c7e89fbf3fd92952956.tar.gz
squashfs: be more careful about metadata corruption
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>
-rw-r--r--fs/squashfs/cache.c3
-rw-r--r--fs/squashfs/file.c8
-rw-r--r--fs/squashfs/fragment.c4
-rw-r--r--fs/squashfs/squashfs_fs.h6
4 files changed, 16 insertions, 5 deletions
diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c
index 23813c078cc9..0839efa720b3 100644
--- a/fs/squashfs/cache.c
+++ b/fs/squashfs/cache.c
@@ -350,6 +350,9 @@ int squashfs_read_metadata(struct super_block *sb, void *buffer,
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) {
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 13d80947bf9e..fcff2e0487fe 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -194,7 +194,11 @@ static long long read_indexes(struct super_block *sb, int n,
}
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 *inode, int index, u64 *block)
sizeof(size));
if (res < 0)
return res;
- return le32_to_cpu(size);
+ return squashfs_block_size(size);
}
/* Copy data into page cache */
diff --git a/fs/squashfs/fragment.c b/fs/squashfs/fragment.c
index 0ed6edbc5c71..86ad9a4b8c36 100644
--- a/fs/squashfs/fragment.c
+++ b/fs/squashfs/fragment.c
@@ -61,9 +61,7 @@ int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment,
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);
}
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 24d12fd14177..4e6853f084d0 100644
--- 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