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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: Phillip Lougher <phillip@lougher.demon.co.uk>
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commit 118e1ef6fabfc023126e6075f6ac0fc729cb5285 1 parent 2450cf5
@plougher plougher authored
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13 fs/squashfs/block.c
@@ -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 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
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;
}
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4 fs/squashfs/cache.c
@@ -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;
}
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2  fs/squashfs/squashfs.h
@@ -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);
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2  fs/squashfs/super.c
@@ -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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