Commit 118e1ef6 authored by Phillip Lougher's avatar Phillip Lougher
Browse files

Squashfs: Fix oops when reading fsfuzzer corrupted filesystems 



This fixes a code regression caused by the recent mainlining changes.
The recent code changes call zlib_inflate repeatedly, decompressing into
separate 4K buffers, this code didn't check for the possibility that
zlib_inflate might ask for too many buffers when decompressing corrupted
data.

Signed-off-by: default avatarPhillip Lougher <phillip@lougher.demon.co.uk>
parent 2450cf51

fs/squashfs/block.c

+11 −2
Original line number Diff line number Diff line
@@ -80,7 +80,7 @@ static struct buffer_head *get_block_length(struct super_block *sb, 
 * generated a larger block - this does occasionally happen with zlib).

 */

int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,

			int length, u64 *next_index, int srclength)

			int length, u64 *next_index, int srclength, int pages)

{

	struct squashfs_sb_info *msblk = sb->s_fs_info;

	struct buffer_head **bh;
@@ -185,6 +185,14 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index, 
			}



			if (msblk->stream.avail_out == 0) {

				if (page == pages) {

					ERROR("zlib_inflate tried to "

						"decompress too much data, "

						"expected %d bytes.  Zlib "

						"data probably corrupt\n",

						srclength);

					goto release_mutex;

				}

				msblk->stream.next_out = buffer[page++];

				msblk->stream.avail_out = PAGE_CACHE_SIZE;

			}
@@ -268,7 +276,8 @@ block_release: 
		put_bh(bh[k]);



read_failure:

	ERROR("sb_bread failed reading block 0x%llx\n", cur_index);

	ERROR("squashfs_read_data failed to read block 0x%llx\n",

					(unsigned long long) index);

	kfree(bh);

	return -EIO;

}

fs/squashfs/cache.c

+2 −2
Original line number Diff line number Diff line
@@ -119,7 +119,7 @@ struct squashfs_cache_entry *squashfs_cache_get(struct super_block *sb, 


			entry->length = squashfs_read_data(sb, entry->data,

				block, length, &entry->next_index,

				cache->block_size);

				cache->block_size, cache->pages);



			spin_lock(&cache->lock);
@@ -406,7 +406,7 @@ int squashfs_read_table(struct super_block *sb, void *buffer, u64 block, 
	for (i = 0; i < pages; i++, buffer += PAGE_CACHE_SIZE)

		data[i] = buffer;

	res = squashfs_read_data(sb, data, block, length |

		SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length);

		SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length, pages);

	kfree(data);

	return res;

}

fs/squashfs/squashfs.h

+1 −1
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ static inline struct squashfs_inode_info *squashfs_i(struct inode *inode) 


/* block.c */

extern int squashfs_read_data(struct super_block *, void **, u64, int, u64 *,

				int);

				int, int);



/* cache.c */

extern struct squashfs_cache *squashfs_cache_init(char *, int, int);

fs/squashfs/super.c

+1 −1
Original line number Diff line number Diff line
@@ -389,7 +389,7 @@ static int __init init_squashfs_fs(void) 
		return err;

	}



	printk(KERN_INFO "squashfs: version 4.0 (2009/01/03) "

	printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "

		"Phillip Lougher\n");



	return 0;

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