Squashfs: Fix oops when reading fsfuzzer corrupted filesystems
Phillip Lougher [Thu, 5 Mar 2009 00:31:12 +0000 (00:31 +0000)]
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>

fs/squashfs/block.c
fs/squashfs/cache.c
fs/squashfs/squashfs.h
fs/squashfs/super.c

index c837dfc..321728f 100644 (file)
@@ -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;
 }
index f29eda1..1c4739e 100644 (file)
@@ -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;
 }
index 6b2515d..0e9feb6 100644 (file)
@@ -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);
index 071df5b..681ec0d 100644 (file)
@@ -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;