[PATCH 3.2 203/221] rds: avoid potential stack overflow

Ben Hutchings
2015-05-05T02:30:00Z

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit f862e07cf95d5b62a5fc5e981dd7d0dbaf33a501 ]

The rds_iw_update_cm_id function stores a large 'struct rds_sock' object
on the stack in order to pass a pair of addresses. This happens to just
fit withint the 1024 byte stack size warning limit on x86, but just
exceed that limit on ARM, which gives us this warning:

net/rds/iw_rdma.c:200:1: warning: the frame size of 1056 bytes is larger than 1024 bytes [-Wframe-larger-than=]

As the use of this large variable is basically bogus, we can rearrange
the code to not do that. Instead of passing an rds socket into
rds_iw_get_device, we now just pass the two addresses that we have
available in rds_iw_update_cm_id, and we change rds_iw_get_mr accordingly,
to create two address structures on the stack there.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/rds/iw_rdma.c | 40 ++++++++++++++++++++++------------------
1 file changed, 22 insertions(+), 18 deletions(-)

--- a/net/rds/iw_rdma.c
+++ b/net/rds/iw_rdma.c
@@ -88,7 +88,9 @@ static unsigned int rds_iw_unmap_fastreg
int *unpinned);
static void rds_iw_destroy_fastreg(struct rds_iw_mr_pool *pool, struct rds_iw_mr *ibmr);

-static int rds_iw_get_device(struct rds_sock *rs, struct rds_iw_device **rds_iwdev, struct rdma_cm_id **cm_id)
+static int rds_iw_get_device(struct sockaddr_in *src, struct sockaddr_in *dst,
+ struct rds_iw_device **rds_iwdev,
+ struct rdma_cm_id **cm_id)
{
struct rds_iw_device *iwdev;
struct rds_iw_cm_id *i_cm_id;
@@ -112,15 +114,15 @@ static int rds_iw_get_device(struct rds_
src_addr->sin_port,
dst_addr->sin_addr.s_addr,
dst_addr->sin_port,
- rs->rs_bound_addr,
- rs->rs_bound_port,
- rs->rs_conn_addr,
- rs->rs_conn_port);
+ src->sin_addr.s_addr,
+ src->sin_port,
+ dst->sin_addr.s_addr,
+ dst->sin_port);
#ifdef WORKING_TUPLE_DETECTION
- if (src_addr->sin_addr.s_addr == rs->rs_bound_addr &&
- src_addr->sin_port == rs->rs_bound_port &&
- dst_addr->sin_addr.s_addr == rs->rs_conn_addr &&
- dst_addr->sin_port == rs->rs_conn_port) {
+ if (src_addr->sin_addr.s_addr == src->sin_addr.s_addr &&
+ src_addr->sin_port == src->sin_port &&
+ dst_addr->sin_addr.s_addr == dst->sin_addr.s_addr &&
+ dst_addr->sin_port == dst->sin_port) {
#else
/* FIXME - needs to compare the local and remote
* ipaddr/port tuple, but the ipaddr is the only
@@ -128,7 +130,7 @@ static int rds_iw_get_device(struct rds_
* zero'ed. It doesn't appear to be properly populated
* during connection setup...
*/
- if (src_addr->sin_addr.s_addr == rs->rs_bound_addr) {
+ if (src_addr->sin_addr.s_addr == src->sin_addr.s_addr) {
#endif
spin_unlock_irq(&iwdev->spinlock);
*rds_iwdev = iwdev;
@@ -180,19 +182,13 @@ int rds_iw_update_cm_id(struct rds_iw_de
{
struct sockaddr_in *src_addr, *dst_addr;
struct rds_iw_device *rds_iwdev_old;
- struct rds_sock rs;
struct rdma_cm_id *pcm_id;
int rc;

src_addr = (struct sockaddr_in *)&cm_id->route.addr.src_addr;
dst_addr = (struct sockaddr_in *)&cm_id->route.addr.dst_addr;

- rs.rs_bound_addr = src_addr->sin_addr.s_addr;
- rs.rs_bound_port = src_addr->sin_port;
- rs.rs_conn_addr = dst_addr->sin_addr.s_addr;
- rs.rs_conn_port = dst_addr->sin_port;
-
- rc = rds_iw_get_device(&rs, &rds_iwdev_old, &pcm_id);
+ rc = rds_iw_get_device(src_addr, dst_addr, &rds_iwdev_old, &pcm_id);
if (rc)
rds_iw_remove_cm_id(rds_iwdev, cm_id);

@@ -611,9 +607,17 @@ void *rds_iw_get_mr(struct scatterlist *
struct rds_iw_device *rds_iwdev;
struct rds_iw_mr *ibmr = NULL;
struct rdma_cm_id *cm_id;
+ struct sockaddr_in src = {
+ .sin_addr.s_addr = rs->rs_bound_addr,
+ .sin_port = rs->rs_bound_port,
+ };
+ struct sockaddr_in dst = {
+ .sin_addr.s_addr = rs->rs_conn_addr,
+ .sin_port = rs->rs_conn_port,
+ };
int ret;

- ret = rds_iw_get_device(rs, &rds_iwdev, &cm_id);
+ ret = rds_iw_get_device(&src, &dst, &rds_iwdev, &cm_id);
if (ret || !cm_id) {
ret = -ENODEV;
goto out;