[3.13.y.z extended stable] Patch "iscsi-target: Fix wrong buffer / buffer overrun in iscsi_change_param_value()" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Tue Jun 17 21:42:45 UTC 2014


This is a note to let you know that I have just added a patch titled

    iscsi-target: Fix wrong buffer / buffer overrun in iscsi_change_param_value()

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From caea43f2aad152a5bd1f319891df007f4dfbe424 Mon Sep 17 00:00:00 2001
From: Roland Dreier <roland at purestorage.com>
Date: Thu, 29 May 2014 13:32:30 -0700
Subject: iscsi-target: Fix wrong buffer / buffer overrun in
 iscsi_change_param_value()

commit 79d59d08082dd0a0a18f8ceb78c99f9f321d72aa upstream.

In non-leading connection login, iscsi_login_non_zero_tsih_s1() calls
iscsi_change_param_value() with the buffer it uses to hold the login
PDU, not a temporary buffer.  This leads to the login header getting
corrupted and login failing for non-leading connections in MC/S.

Fix this by adding a wrapper iscsi_change_param_sprintf() that handles
the temporary buffer itself to avoid confusion.  Also handle sending a
reject in case of failure in the wrapper, which lets the calling code
get quite a bit smaller and easier to read.

Finally, bump the size of the temporary buffer from 32 to 64 bytes to be
safe, since "MaxRecvDataSegmentLength=" by itself is 25 bytes; with a
trailing NUL, a value >= 1M will lead to a buffer overrun.  (This isn't
the default but we don't need to run right at the ragged edge here)

Reported-by: Santosh Kulkarni <santosh.kulkarni at calsoftinc.com>
Signed-off-by: Roland Dreier <roland at purestorage.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
[ kamal: backport to 3.13-stable: omit inapplicable bit from
  iscsi_login_zero_tsih_s2 ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/target/iscsi/iscsi_target_login.c | 57 +++++++++++++++----------------
 1 file changed, 28 insertions(+), 29 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index e29279e..369ef10 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -249,6 +249,28 @@ static void iscsi_login_set_conn_values(
 	mutex_unlock(&auth_id_lock);
 }

+static __printf(2, 3) int iscsi_change_param_sprintf(
+	struct iscsi_conn *conn,
+	const char *fmt, ...)
+{
+	va_list args;
+	unsigned char buf[64];
+
+	memset(buf, 0, sizeof buf);
+
+	va_start(args, fmt);
+	vsnprintf(buf, sizeof buf, fmt, args);
+	va_end(args);
+
+	if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
+		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
+				ISCSI_LOGIN_STATUS_NO_RESOURCES);
+		return -1;
+	}
+
+	return 0;
+}
+
 /*
  *	This is the leading connection of a new session,
  *	or session reinstatement.
@@ -337,7 +359,6 @@ static int iscsi_login_zero_tsih_s2(
 {
 	struct iscsi_node_attrib *na;
 	struct iscsi_session *sess = conn->sess;
-	unsigned char buf[32];
 	bool iser = false;

 	sess->tpg = conn->tpg;
@@ -378,26 +399,16 @@ static int iscsi_login_zero_tsih_s2(
 	 *
 	 * In our case, we have already located the struct iscsi_tiqn at this point.
 	 */
-	memset(buf, 0, 32);
-	sprintf(buf, "TargetPortalGroupTag=%hu", sess->tpg->tpgt);
-	if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
-		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
-				ISCSI_LOGIN_STATUS_NO_RESOURCES);
+	if (iscsi_change_param_sprintf(conn, "TargetPortalGroupTag=%hu", sess->tpg->tpgt))
 		return -1;
-	}

 	/*
 	 * Workaround for Initiators that have broken connection recovery logic.
 	 *
 	 * "We would really like to get rid of this." Linux-iSCSI.org team
 	 */
-	memset(buf, 0, 32);
-	sprintf(buf, "ErrorRecoveryLevel=%d", na->default_erl);
-	if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
-		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
-				ISCSI_LOGIN_STATUS_NO_RESOURCES);
+	if (iscsi_change_param_sprintf(conn, "ErrorRecoveryLevel=%d", na->default_erl))
 		return -1;
-	}

 	if (iscsi_login_disable_FIM_keys(conn->param_list, conn) < 0)
 		return -1;
@@ -409,12 +420,9 @@ static int iscsi_login_zero_tsih_s2(
 		unsigned long mrdsl, off;
 		int rc;

-		sprintf(buf, "RDMAExtensions=Yes");
-		if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
-			iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
-				ISCSI_LOGIN_STATUS_NO_RESOURCES);
+		if (iscsi_change_param_sprintf(conn, "RDMAExtensions=Yes"))
 			return -1;
-		}
+
 		/*
 		 * Make MaxRecvDataSegmentLength PAGE_SIZE aligned for
 		 * Immediate Data + Unsolicitied Data-OUT if necessary..
@@ -444,12 +452,8 @@ static int iscsi_login_zero_tsih_s2(
 		pr_warn("Aligning ISER MaxRecvDataSegmentLength: %lu down"
 			" to PAGE_SIZE\n", mrdsl);

-		sprintf(buf, "MaxRecvDataSegmentLength=%lu\n", mrdsl);
-		if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
-			iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
-				ISCSI_LOGIN_STATUS_NO_RESOURCES);
+		if (iscsi_change_param_sprintf(conn, "MaxRecvDataSegmentLength=%lu\n", mrdsl))
 			return -1;
-		}
 	}

 	return 0;
@@ -591,13 +595,8 @@ static int iscsi_login_non_zero_tsih_s2(
 	 *
 	 * In our case, we have already located the struct iscsi_tiqn at this point.
 	 */
-	memset(buf, 0, 32);
-	sprintf(buf, "TargetPortalGroupTag=%hu", sess->tpg->tpgt);
-	if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
-		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
-				ISCSI_LOGIN_STATUS_NO_RESOURCES);
+	if (iscsi_change_param_sprintf(conn, "TargetPortalGroupTag=%hu", sess->tpg->tpgt))
 		return -1;
-	}

 	return iscsi_login_disable_FIM_keys(conn->param_list, conn);
 }
--
1.9.1





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