From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:28062 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754785Ab3GaBea (ORCPT ); Tue, 30 Jul 2013 21:34:30 -0400 From: Liu Bo To: linux-btrfs@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH RESEND] Btrfs: fix crash regarding to ulist_add_merge Date: Wed, 31 Jul 2013 09:34:14 +0800 Message-Id: <1375234454-6061-1-git-send-email-bo.li.liu@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Several users reported this crash of NULL pointer or general protection, the story is that we add a rbtree for speedup ulist iteration, and we use krealloc() to address ulist growth, and krealloc() use memcpy to copy old data to new memory area, so it's OK for an array as it doesn't use pointers while it's not OK for a rbtree as it uses pointers. So krealloc() will mess up our rbtree and it ends up with crash. Cc: stable@vger.kernel.org Reviewed-by: Wang Shilong Reviewed-by: Jan Schmidt Signed-off-by: Liu Bo Signed-off-by: Josef Bacik --- Cc -stable! fs/btrfs/ulist.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c index 7b417e2..b0a523b2 100644 --- a/fs/btrfs/ulist.c +++ b/fs/btrfs/ulist.c @@ -205,6 +205,10 @@ int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, u64 new_alloced = ulist->nodes_alloced + 128; struct ulist_node *new_nodes; void *old = NULL; + int i; + + for (i = 0; i < ulist->nnodes; i++) + rb_erase(&ulist->nodes[i].rb_node, &ulist->root); /* * if nodes_alloced == ULIST_SIZE no memory has been allocated @@ -224,6 +228,17 @@ int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, ulist->nodes = new_nodes; ulist->nodes_alloced = new_alloced; + + /* + * krealloc actually uses memcpy, which does not copy rb_node + * pointers, so we have to do it ourselves. Otherwise we may + * be bitten by crashes. + */ + for (i = 0; i < ulist->nnodes; i++) { + ret = ulist_rbtree_insert(ulist, &ulist->nodes[i]); + if (ret < 0) + return ret; + } } ulist->nodes[ulist->nnodes].val = val; ulist->nodes[ulist->nnodes].aux = aux; -- 1.8.1.4