[PATCH AUTOSEL for 4.4 049/101] infiniband/uverbs: Fix integer overflows

[Sasha Levin]

From: Vlad Tsyrklevich <vlad@xxxxxxxxxxxxxxx>

[ Upstream commit 4f7f4dcfff2c19debbcdbcc861c325610a15e0c5 ]

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@xxxxxxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/infiniband/core/uverbs_cmd.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index b7a73f1a8beb..3eb967521917 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2436,9 +2436,13 @@ 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,
@@ -2665,6 +2669,13 @@ 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);
-- 
2.14.1