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Subject[PATCH 3.10 08/18] iscsi-target: Fix wrong buffer / buffer overrun in iscsi_change_param_value()
Date
3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Roland Dreier <roland@purestorage.com>

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)

(Fix up context changes for v3.10.y - nab)

Reported-by: Santosh Kulkarni <santosh.kulkarni@calsoftinc.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/target/iscsi/iscsi_target_login.c | 50 ++++++++++++++++--------------
1 file changed, 27 insertions(+), 23 deletions(-)

--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -250,6 +250,28 @@ 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.
@@ -339,7 +361,6 @@ 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;
@@ -380,26 +401,16 @@ 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", ISCSI_TPG_S(sess)->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;
@@ -411,12 +422,9 @@ 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..
@@ -446,12 +454,8 @@ 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;



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