x86/PCI: Fix Broadcom CNB20LE unintended sign extension (redux)

BugLink: https://bugs.launchpad.net/bugs/1837664
[ Upstream commit 53bb565fc5439f2c8c57a786feea5946804aa3e9 ]

In the expression "word1 << 16", word1 starts as u16, but is promoted to a
signed int, then sign-extended to resource_size_t, which is probably not
what was intended.  Cast to resource_size_t to avoid the sign extension.

This fixes an identical issue as fixed by commit 0b2d70764bb3 ("x86/PCI:
Fix Broadcom CNB20LE unintended sign extension") back in 2014.

Detected by CoverityScan, CID#138749, 138750 ("Unintended sign extension")

Fixes: 3f6ea84a3035 ("PCI: read memory ranges out of Broadcom CNB20LE host bridge")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/x86/pci/broadcom_bus.c b/arch/x86/pci/broadcom_bus.c
index 526536c81ddc41d395fd971d909a3b687e46d989..ca1e8e6dccc8afc235402e2ef7efd0a86a936a07 100644 (file)
--- a/arch/x86/pci/broadcom_bus.c
+++ b/arch/x86/pci/broadcom_bus.c
@@ -50,8 +50,8 @@ static void __init cnb20le_res(u8 bus, u8 slot, u8 func)
        word1 = read_pci_config_16(bus, slot, func, 0xc0);
        word2 = read_pci_config_16(bus, slot, func, 0xc2);
        if (word1 != word2) {
-               res.start = (word1 << 16) | 0x0000;
-               res.end   = (word2 << 16) | 0xffff;
+               res.start = ((resource_size_t) word1 << 16) | 0x0000;
+               res.end   = ((resource_size_t) word2 << 16) | 0xffff;
                res.flags = IORESOURCE_MEM;
                update_res(info, res.start, res.end, res.flags, 0);
        }