RDS: Heap OOB write in rds_message_alloc_sgs()

commit c095508770aebf1b9218e77026e48345d719b17c upstream.

When args->nr_local is 0, nr_pages gets also 0 due some size
calculation via rds_rm_size(), which is later used to allocate
pages for DMA, this bug produces a heap Out-Of-Bound write access
to a specific memory region.

Signed-off-by: Mohamed Ghannam <simo.ghannam@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/rds/rdma.c b/net/rds/rdma.c
index 4e37c1c..6bb8a4c 100644 (file)
--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -516,6 +516,9 @@ int rds_rdma_extra_size(struct rds_rdma_args *args)
 
        local_vec = (struct rds_iovec __user *)(unsigned long) args->local_vec_addr;
 
 
        local_vec = (struct rds_iovec __user *)(unsigned long) args->local_vec_addr;
 

+       if (args->nr_local == 0)
+               return -EINVAL;
+

        /* figure out the number of pages in the vector */
        for (i = 0; i < args->nr_local; i++) {
                if (copy_from_user(&vec, &local_vec[i],
        /* figure out the number of pages in the vector */
        for (i = 0; i < args->nr_local; i++) {
                if (copy_from_user(&vec, &local_vec[i],