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Date: Mon, 9 May 2011 17:57:10 +0200 From: Lukas Czerner <lczerner@...hat.com> To: linux-ext4@...r.kernel.org Cc: tytso@....edu, sandeen@...hat.com, Lukas Czerner <lczerner@...hat.com> Subject: [PATCH 4/4] ext4: fix possible use-after-free 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 <lczerner@...hat.com> --- fs/ext4/super.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c379af6..6a8e48f 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2721,14 +2721,16 @@ 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; -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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