From 166ae5a418756dacd2e8883c6f562c2d0ce2db2d Mon Sep 17 00:00:00 2001 From: Zach Brown Date: Fri, 9 May 2014 17:15:10 -0400 Subject: [PATCH] btrfs: fix inline compressed read err corruption uncompress_inline() is dropping the error from btrfs_decompress() after testing it and zeroing the page that was supposed to hold decompressed data. This can silently turn compressed inline data in to zeros if decompression fails due to corrupt compressed data or memory allocation failure. I verified this by manually forcing the error from btrfs_decompress() for a silly named copy of od: if (!strcmp(current->comm, "failod")) ret = -ENOMEM; # od -x /mnt/btrfs/dir/80 | head -1 0000000 3031 3038 310a 2d30 6f70 6e69 0a74 3031 # echo 3 > /proc/sys/vm/drop_caches # cp $(which od) /tmp/failod # /tmp/failod -x /mnt/btrfs/dir/80 | head -1 0000000 0000 0000 0000 0000 0000 0000 0000 0000 The fix is to pass the error to its caller. Which still has a BUG_ON(). So we fix that too. There seems to be no reason for the zeroing of the page on the error from btrfs_decompress() but not from the allocation error a few lines above. So the page zeroing is removed. Signed-off-by: Zach Brown Reviewed-by: David Sterba Signed-off-by: Chris Mason --- fs/btrfs/inode.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5f805bc944fa..24dfa27a4f76 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6086,16 +6086,8 @@ static noinline int uncompress_inline(struct btrfs_path *path, max_size = min_t(unsigned long, PAGE_CACHE_SIZE, max_size); ret = btrfs_decompress(compress_type, tmp, page, extent_offset, inline_size, max_size); - if (ret) { - char *kaddr = kmap_atomic(page); - unsigned long copy_size = min_t(u64, - PAGE_CACHE_SIZE - pg_offset, - max_size - extent_offset); - memset(kaddr + pg_offset, 0, copy_size); - kunmap_atomic(kaddr); - } kfree(tmp); - return 0; + return ret; } /* @@ -6296,7 +6288,10 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page, ret = uncompress_inline(path, inode, page, pg_offset, extent_offset, item); - BUG_ON(ret); /* -ENOMEM */ + if (ret) { + err = ret; + goto out; + } } else { map = kmap(page); read_extent_buffer(leaf, map + pg_offset, ptr, -- GitLab