From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL 4.20 71/72] autofs: drop dentry reference only when it is never used Date: Sat, 23 Feb 2019 16:04:21 -0500 Message-ID: <20190223210422.199966-71-sashal@kernel.org> References: <20190223210422.199966-1-sashal@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550955997; bh=Z89t9QdpXqF4+TcRXl/MfORsjP6JrY8g4Bg32oSTBrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=futBeUWqHTcPPbDv0+4syvhRCmTbwhW+PrF7Ak5td0B9hihB4vWfrV+DANJ3s+z2b wZbYQ79FPi5arBciNNUKEhSsmrfNXjDjmmqEKxUiU3pgIuiilSZbq+7wwST1AYQEcc k0PpqOjSTwXQqoh5W92VaxHn//VgkYH1HEZ+JMoA= In-Reply-To: <20190223210422.199966-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pan Bian , Ian Kent , Andrew Morton , Linus Torvalds , Sasha Levin , autofs@vger.kernel.org From: Pan Bian [ Upstream commit 63ce5f552beb9bdb41546b3a26c4374758b21815 ] autofs_expire_run() calls dput(dentry) to drop the reference count of dentry. However, dentry is read via autofs_dentry_ino(dentry) after that. This may result in a use-free-bug. The patch drops the reference count of dentry only when it is never used. Link: http://lkml.kernel.org/r/154725122396.11260.16053424107144453867.stgit@pluto-themaw-net Signed-off-by: Pan Bian Signed-off-by: Ian Kent Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/autofs/expire.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c index d441244b79df9..28d9c2b1b3bb3 100644 --- a/fs/autofs/expire.c +++ b/fs/autofs/expire.c @@ -596,7 +596,6 @@ int autofs_expire_run(struct super_block *sb, pkt.len = dentry->d_name.len; memcpy(pkt.name, dentry->d_name.name, pkt.len); pkt.name[pkt.len] = '\0'; - dput(dentry); if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire))) ret = -EFAULT; @@ -609,6 +608,8 @@ int autofs_expire_run(struct super_block *sb, complete_all(&ino->expire_complete); spin_unlock(&sbi->fs_lock); + dput(dentry); + return ret; } -- 2.19.1