@@ -224,6 +224,9 @@ struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents)
WARN_ON(rm->m_used_sgs + nents > rm->m_total_sgs);
WARN_ON(!nents);
+ if (rm->m_used_sgs + nents > rm->m_total_sgs)
+ return NULL;
+
sg_ret = &sg_first[rm->m_used_sgs];
sg_init_table(sg_ret, nents);
rm->m_used_sgs += nents;
@@ -246,6 +249,8 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in
rm->m_inc.i_hdr.h_len = cpu_to_be32(total_len);
rm->data.op_nents = ceil(total_len, PAGE_SIZE);
rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs);
+ if (!rm->data.op_sg)
+ return ERR_PTR(-ENOMEM);
for (i = 0; i < rm->data.op_nents; ++i) {
sg_set_page(&rm->data.op_sg[i],
@@ -607,6 +607,10 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
op->op_recverr = rs->rs_recverr;
WARN_ON(!nr_pages);
op->op_sg = rds_message_alloc_sgs(rm, nr_pages);
+ if (!op->op_sg) {
+ ret = -ENOMEM;
+ goto out;
+ }
if (op->op_notify || op->op_recverr) {
/* We allocate an uninitialized notifier here, because
@@ -807,6 +811,10 @@ int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
rm->atomic.op_active = 1;
rm->atomic.op_recverr = rs->rs_recverr;
rm->atomic.op_sg = rds_message_alloc_sgs(rm, 1);
+ if (!rm->atomic.op_sg) {
+ ret = -ENOMEM;
+ goto err;
+ }
/* verify 8 byte-aligned */
if (args->local_addr & 0x7) {
@@ -973,6 +973,10 @@ int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
/* Attach data to the rm */
if (payload_len) {
rm->data.op_sg = rds_message_alloc_sgs(rm, ceil(payload_len, PAGE_SIZE));
+ if (!rm->data.op_sg) {
+ ret = -ENOMEM;
+ goto out;
+ }
ret = rds_message_copy_from_user(rm, msg->msg_iov, payload_len);
if (ret)
goto out;
Even with the previous fix, we still are reading the iovecs once to determine SGs needed, and then again later on. Preallocating space for sg lists as part of rds_message seemed like a good idea but it might be better to not do this. While working to redo that code, this patch attempts to protect against userspace rewriting the rds_iovec array between the first and second accesses. The consequences of this would be either a too-small or too-large sg list array. Too large is not an issue. This patch changes all callers of message_alloc_sgs to handle running out of preallocated sgs, and fail gracefully. Signed-off-by: Andy Grover <andy.grover@oracle.com> --- net/rds/message.c | 5 +++++ net/rds/rdma.c | 8 ++++++++ net/rds/send.c | 4 ++++ 3 files changed, 17 insertions(+), 0 deletions(-)