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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Jason Gunthorpe" <jgg@mellanox.com>,
        "Leon Romanovsky" <leonro@mellanox.com>,
        "Ran Rozenstein" <ranro@mellanox.com>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.203293351@decadent.org.uk>
Subject: [PATCH 3.16 224/366] RDMA/uverbs: Don't fail in creation of
 multiple flows
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Leon Romanovsky <leonro@mellanox.com>

commit fe48aecb4df837540f13b5216f27ddb306aaf4b9 upstream.

The conversion from offsetof() calculations to sizeof()
wrongly behaved for missed exact size and in scenario with
more than one flow.

In such scenario we got "create flow failed, flow 10: 8 bytes
left from uverb cmd" error, which is wrong because the size of
kern_spec is exactly 8 bytes, and we were not supposed to fail.

Fixes: 4fae7f170416 ("RDMA/uverbs: Fix slab-out-of-bounds in ib_uverbs_ex_create_flow")
Reported-by: Ran Rozenstein <ranro@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/infiniband/core/uverbs_cmd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2761,7 +2761,7 @@ int ib_uverbs_ex_create_flow(struct ib_u
 	kern_spec = kern_flow_attr->flow_specs;
 	ib_spec = flow_attr + 1;
 	for (i = 0; i < flow_attr->num_of_specs &&
-			cmd.flow_attr.size > sizeof(*kern_spec) &&
+			cmd.flow_attr.size >= sizeof(*kern_spec) &&
 			cmd.flow_attr.size >= kern_spec->size;
 	     i++) {
 		err = kern_spec_to_ib_spec(