linux-kernel - [PATCH] PCI: endpoint: cast the page number to phys_addr

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Message-Id: <1570240177-8934-1-git-send-email-alan.mikhak@sifive.com>
Date:   Fri,  4 Oct 2019 18:49:37 -0700
From:   Alan Mikhak <alan.mikhak@...ive.com>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        kishon@...com, lorenzo.pieralisi@....com, bhelgaas@...gle.com,
        palmer@...ive.com, paul.walmsley@...ive.com
Cc:     Alan Mikhak <alan.mikhak@...ive.com>
Subject: [PATCH] PCI: endpoint: cast the page number to phys_addr_t

From: Alan Mikhak <alan.mikhak@...ive.com>

Modify pci_epc_mem_alloc_addr() to cast the variable 'pageno'
from type 'int' to 'phys_addr_t' before shifting left. This
cast is needed to avoid treating bit 31 of 'pageno' as the
sign bit which would otherwise get sign-extended to produce
a negative value. When added to the base address of PCI memory
space, the negative value would produce an invalid physical
address which falls before the start of the PCI memory space.

Signed-off-by: Alan Mikhak <alan.mikhak@...ive.com>
---
 drivers/pci/endpoint/pci-epc-mem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-epc-mem.c b/drivers/pci/endpoint/pci-epc-mem.c
index 2bf8bd1f0563..d2b174ce15de 100644
--- a/drivers/pci/endpoint/pci-epc-mem.c
+++ b/drivers/pci/endpoint/pci-epc-mem.c
@@ -134,7 +134,7 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
 	if (pageno < 0)
 		return NULL;
 
-	*phys_addr = mem->phys_base + (pageno << page_shift);
+	*phys_addr = mem->phys_base + ((phys_addr_t)pageno << page_shift);
 	virt_addr = ioremap(*phys_addr, size);
 	if (!virt_addr)
 		bitmap_release_region(mem->bitmap, pageno, order);
-- 
2.7.4