linux-kernel - [PATCH 2/5] staging/lustre/lnet: Fix use after free in ksocknal

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Date:	Thu, 23 Jan 2014 23:45:05 -0500
From:	Oleg Drokin <green@...uxhacker.ru>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org
Cc:	Oleg Drokin <green@...uxhacker.ru>,
	Oleg Drokin <oleg.drokin@...el.com>
Subject: [PATCH 2/5] staging/lustre/lnet: Fix use after free in ksocknal_send

Call to ksocknal_launch_packet might schedule a callback that
might free the just sent message, and so subsequent access to it
via lntmsg->msg_vmflush goes to freed memory.

Instead we'll just remember if we are in the vmflush thread and
only restore if we happened to set mempressure flag.

Signed-off-by: Oleg Drokin <oleg.drokin@...el.com>
Reviewed-on: http://review.whamcloud.com/8667
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4360
Reviewed-by: Liang Zhen <liang.zhen@...el.com>
Reviewed-by: Amir Shehata <amir.shehata@...el.com>
---
 drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c
index 68a4f52..b7b53b5 100644
--- a/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c
+++ b/drivers/staging/lustre/lnet/klnds/socklnd/socklnd_cb.c
@@ -924,7 +924,7 @@ ksocknal_launch_packet (lnet_ni_t *ni, ksock_tx_t *tx, lnet_process_id_t id)
 int
 ksocknal_send(lnet_ni_t *ni, void *private, lnet_msg_t *lntmsg)
 {
-	int	       mpflag = 0;
+	int	       mpflag = 1;
 	int	       type = lntmsg->msg_type;
 	lnet_process_id_t target = lntmsg->msg_target;
 	unsigned int      payload_niov = lntmsg->msg_niov;
@@ -993,8 +993,9 @@ ksocknal_send(lnet_ni_t *ni, void *private, lnet_msg_t *lntmsg)
 
 	/* The first fragment will be set later in pro_pack */
 	rc = ksocknal_launch_packet(ni, tx, target);
-	if (lntmsg->msg_vmflush)
+	if (!mpflag)
 		cfs_memory_pressure_restore(mpflag);
+
 	if (rc == 0)
 		return (0);
 
-- 
1.8.5.3

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