Commit f1fee653 authored May 17, 2016 by Zhao Lei Committed by David Sterba May 25, 2016

btrfs: scrub: Set bbio to NULL before calling btrfs_map_block



We usually call btrfs_put_bbio() when btrfs_map_block() failed,
btrfs_put_bbio() works right whether bbio is a valid value, or NULL.

But there is a exception, in some case, btrfs_map_block() will return
fail without touching *bbio(keeping its original value), and if bbio
was not initialized yet, invalid memory accessing will happened.

Above case is in scrub_missing_raid56_pages(), and similar case in
scrub_raid56_parity().

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 2d324f59

fs/btrfs/scrub.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2181,7 +2181,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock)
		struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
		u64 length = sblock->page_count * PAGE_SIZE;
		u64 logical = sblock->pagev[0]->logical;
		struct btrfs_bio *bbio;
		struct btrfs_bio *bbio = NULL;
		struct bio *bio;
		struct btrfs_raid_bio *rbio;
		int ret;
		@@ -2982,6 +2982,7 @@ static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
		extent_len);

		mapped_length = extent_len;
		bbio = NULL;
		ret = btrfs_map_block(fs_info, READ, extent_logical,
		&mapped_length, &bbio, 0);
		if (!ret) {