On Thu, Apr 03, 2014 at 02:56:26PM -0600, Bjorn Helgaas wrote:
> Coverity complains about unintended sign extension in cnb20le_res() in
> arch/x86/pci/broadcom_bus.c here:
>
> 60 word1 = read_pci_config_16(bus, slot, func, 0xc4);
> 61 word2 = read_pci_config_16(bus, slot, func, 0xc6);
> 62 if (word1 != word2) {
>
> CID 138749 (#1 of 2): Unintended sign extension (SIGN_EXTENSION)
> sign_extension: Suspicious implicit sign extension: word1 with type
> unsigned short (16 bits, unsigned) is promoted in (word1 << 16) | 0 to
> type int (32 bits, signed), then sign-extended to type unsigned long
> long (64 bits, unsigned). If (word1 << 16) | 0 is greater than
> 0x7FFFFFFF, the upper bits of the result will all be 1.
> 63 res.start = (word1 << 16) | 0x0000;
> CID 138750: Unintended sign extension (SIGN_EXTENSION) [select issue]
I propose the following patch for this. Unless there's objection, I'll
queue this for v3.16.
x86/PCI: Fix Broadcom CNB20LE unintended sign extension
From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
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.
Found by Coverity (CID 138749, 138750).
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
arch/x86/pci/broadcom_bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/pci/broadcom_bus.c b/arch/x86/pci/broadcom_bus.c
index 614392ced7d6..bb461cfd01ab 100644
--- a/arch/x86/pci/broadcom_bus.c
+++ b/arch/x86/pci/broadcom_bus.c
@@ -60,8 +60,8 @@ static void __init cnb20le_res(u8 bus, u8 slot, u8 func)
word1 = read_pci_config_16(bus, slot, func, 0xc4);
word2 = read_pci_config_16(bus, slot, func, 0xc6);
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 | IORESOURCE_PREFETCH;
update_res(info, res.start, res.end, res.flags, 0);
}
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
