infiniband/uverbs: Fix integer overflows

The 'num_sge' variable is verfied to be smaller than the 'sge_count'
variable; however, since both are user-controlled it's possible to cause
an integer overflow for the kmalloc multiply on 32-bit platforms
(num_sge and sge_count are both defined u32). By crafting an input that
causes a smaller-than-expected allocation it's possible to write
controlled data out-of-bounds.

Signed-off-by: Vlad Tsyrklevich <vlad@tsyrklevich.net>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 562184e..7a4a10e 100644 (file)
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2104,9 +2104,13 @@ ssize_t ib_uverbs_destroy_qp(struct ib_uverbs_file *file,
 
 static void *alloc_wr(size_t wr_size, __u32 num_sge)
 {
+       if (num_sge >= (U32_MAX - ALIGN(wr_size, sizeof (struct ib_sge))) /
+                      sizeof (struct ib_sge))
+               return NULL;
+
        return kmalloc(ALIGN(wr_size, sizeof (struct ib_sge)) +
                         num_sge * sizeof (struct ib_sge), GFP_KERNEL);
-};
+}
 
 ssize_t ib_uverbs_post_send(struct ib_uverbs_file *file,
                            struct ib_device *ib_dev,
@@ -2334,6 +2338,13 @@ static struct ib_recv_wr *ib_uverbs_unmarshall_recv(const char __user *buf,
                        goto err;
                }
 
+               if (user_wr->num_sge >=
+                   (U32_MAX - ALIGN(sizeof *next, sizeof (struct ib_sge))) /
+                   sizeof (struct ib_sge)) {
+                       ret = -EINVAL;
+                       goto err;
+               }
+
                next = kmalloc(ALIGN(sizeof *next, sizeof (struct ib_sge)) +
                               user_wr->num_sge * sizeof (struct ib_sge),
                               GFP_KERNEL);