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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alex Dewar <alex.dewar90@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.8 185/633] VMCI: check return value of get_user_pages_fast() for errors
Date:   Tue, 27 Oct 2020 14:48:48 +0100
Message-Id: <20201027135531.367726215@linuxfoundation.org>
In-Reply-To: <20201027135522.655719020@linuxfoundation.org>
References: <20201027135522.655719020@linuxfoundation.org>
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From: Alex Dewar <alex.dewar90@gmail.com>

[ Upstream commit 90ca6333fd65f318c47bff425e1ea36c0a5539f6 ]

In a couple of places in qp_host_get_user_memory(),
get_user_pages_fast() is called without properly checking for errors. If
e.g. -EFAULT is returned, this negative value will then be passed on to
qp_release_pages(), which expects a u64 as input.

Fix this by only calling qp_release_pages() when we have a positive
number returned.

Fixes: 06164d2b72aa ("VMCI: queue pairs implementation.")
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Link: https://lore.kernel.org/r/20200825164522.412392-1-alex.dewar90@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/misc/vmw_vmci/vmci_queue_pair.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c
index 8531ae7811956..c49065887e8f5 100644
--- a/drivers/misc/vmw_vmci/vmci_queue_pair.c
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
@@ -657,8 +657,9 @@ static int qp_host_get_user_memory(u64 produce_uva,
 	if (retval < (int)produce_q->kernel_if->num_pages) {
 		pr_debug("get_user_pages_fast(produce) failed (retval=%d)",
 			retval);
-		qp_release_pages(produce_q->kernel_if->u.h.header_page,
-				 retval, false);
+		if (retval > 0)
+			qp_release_pages(produce_q->kernel_if->u.h.header_page,
+					retval, false);
 		err = VMCI_ERROR_NO_MEM;
 		goto out;
 	}
@@ -670,8 +671,9 @@ static int qp_host_get_user_memory(u64 produce_uva,
 	if (retval < (int)consume_q->kernel_if->num_pages) {
 		pr_debug("get_user_pages_fast(consume) failed (retval=%d)",
 			retval);
-		qp_release_pages(consume_q->kernel_if->u.h.header_page,
-				 retval, false);
+		if (retval > 0)
+			qp_release_pages(consume_q->kernel_if->u.h.header_page,
+					retval, false);
 		qp_release_pages(produce_q->kernel_if->u.h.header_page,
 				 produce_q->kernel_if->num_pages, false);
 		err = VMCI_ERROR_NO_MEM;
-- 
2.25.1