Commit ecebf55d authored Nov 25, 2018 by Pan Bian Committed by Jan Kara Nov 27, 2018

ext2: fix potential use after free



The function ext2_xattr_set calls brelse(bh) to drop the reference count
of bh. After that, bh may be freed. However, following brelse(bh),
it reads bh->b_data via macro HDR(bh). This may result in a
use-after-free bug. This patch moves brelse(bh) after reading field.

CC: stable@vger.kernel.org
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Jan Kara <jack@suse.cz>

parent e5f5b717

fs/ext2/xattr.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -612,9 +612,9 @@ skip_replace:
		}

		cleanup:
		brelse(bh);
		if (!(bh && header == HDR(bh)))
		kfree(header);
		brelse(bh);
		up_write(&EXT2_I(inode)->xattr_sem);

		return error;

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