From: Lukas Czerner Date: Fri, 20 May 2011 17:55:29 +0000 (-0400) Subject: ext4: fix possible use-after-free in ext4_remove_li_request() X-Git-Tag: upstream/snapshot3+hdmi~10149^2~26 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1bb933fb1fa8e4cb337a0d5dfd2ff4c0dc2073e8;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git ext4: fix possible use-after-free in ext4_remove_li_request() We need to take reference to the s_li_request after we take a mutex, because it might be freed since then, hence result in accessing old already freed memory. Also we should protect the whole ext4_remove_li_request() because ext4_li_info might be in the process of being freed in ext4_lazyinit_thread(). Signed-off-by: Lukas Czerner Signed-off-by: "Theodore Ts'o" Reviewed-by: Eric Sandeen --- diff --git a/fs/ext4/super.c b/fs/ext4/super.c index fd51a4a..ed5e80e 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2735,14 +2735,16 @@ static void ext4_remove_li_request(struct ext4_li_request *elr) static void ext4_unregister_li_request(struct super_block *sb) { - struct ext4_li_request *elr = EXT4_SB(sb)->s_li_request; - - if (!ext4_li_info) + mutex_lock(&ext4_li_mtx); + if (!ext4_li_info) { + mutex_unlock(&ext4_li_mtx); return; + } mutex_lock(&ext4_li_info->li_list_mtx); - ext4_remove_li_request(elr); + ext4_remove_li_request(EXT4_SB(sb)->s_li_request); mutex_unlock(&ext4_li_info->li_list_mtx); + mutex_unlock(&ext4_li_mtx); } static struct task_struct *ext4_lazyinit_task;