From 9290a9a7c0bcf5400e8dbfbf9707fa68ea3fb338 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Tue, 10 Dec 2013 12:06:35 -0500 Subject: [PATCH] GFS2: Fix use-after-free race when calling gfs2_remove_from_ail Function gfs2_remove_from_ail drops the reference on the bh via brelse. This patch fixes a race condition whereby bh is deferenced after the brelse when setting bd->bd_blkno = bh->b_blocknr; Under certain rare circumstances, bh might be gone or reused, and bd->bd_blkno is set to whatever that memory happens to be, which is often 0. Later, in gfs2_trans_add_unrevoke, that bd fails the test "bd->bd_blkno >= blkno" which causes it to never be freed. The end result is that the bd is never freed from the bufdata cache, which results in this error: slab error in kmem_cache_destroy(): cache `gfs2_bufdata': Can't free all objects Signed-off-by: Bob Peterson Signed-off-by: Steven Whitehouse --- Reading git-format-patch failed