linux-kernel - [PATCH AUTOSEL 4.9 17/98] rxe: Fix a sleep-in-atomic bug in post_one

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Message-Id: <20181025141423.213774-17-sashal@kernel.org>
Date:   Thu, 25 Oct 2018 10:13:02 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jia-Ju Bai <baijiaju1990@....com>,
        Doug Ledford <dledford@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.9 17/98] rxe: Fix a sleep-in-atomic bug in post_one_send

From: Jia-Ju Bai <baijiaju1990@....com>

[ Upstream commit 07d432bb97f19dd5e784175152f9fce3b2646133 ]

The driver may sleep under a spin lock, and the function call path is:
post_one_send (acquire the lock by spin_lock_irqsave)
  init_send_wqe
    copy_from_user --> may sleep

There is no flow that makes "qp->is_user" true, and copy_from_user may
cause bug when a non-user pointer is used. So the lines of copy_from_user
and check of "qp->is_user" are removed.

Signed-off-by: Jia-Ju Bai <baijiaju1990@....com>
Reviewed-by: Leon Romanovsky <leonro@...lanox.com>
Acked-by: Moni Shoua <monis@...lanox.com>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/infiniband/sw/rxe/rxe_verbs.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
index ced416f5dffb..ef13082d6ca1 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -729,13 +729,8 @@ static int init_send_wqe(struct rxe_qp *qp, struct ib_send_wr *ibwr,
 
 		sge = ibwr->sg_list;
 		for (i = 0; i < num_sge; i++, sge++) {
-			if (qp->is_user && copy_from_user(p, (__user void *)
-					    (uintptr_t)sge->addr, sge->length))
-				return -EFAULT;
-
-			else if (!qp->is_user)
-				memcpy(p, (void *)(uintptr_t)sge->addr,
-				       sge->length);
+			memcpy(p, (void *)(uintptr_t)sge->addr,
+					sge->length);
 
 			p += sge->length;
 		}
-- 
2.17.1