* [PATCH] x86/hvm: Fix shifting in stdvga_mem_read()
@ 2020-05-16 19:02 Andrew Cooper
2020-05-18 11:11 ` Jan Beulich
0 siblings, 1 reply; 2+ messages in thread
From: Andrew Cooper @ 2020-05-16 19:02 UTC (permalink / raw)
To: Xen-devel; +Cc: Andrew Cooper, Wei Liu, Jan Beulich, Roger Pau Monné
stdvga_mem_read() has a return type of uint8_t, which promotes to int rather
than unsigned int. Shifting by 24 may hit the sign bit.
Spotted by Coverity.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wl@xen.org>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
xen/arch/x86/hvm/stdvga.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/xen/arch/x86/hvm/stdvga.c b/xen/arch/x86/hvm/stdvga.c
index bd398dbb1b..e2675139e7 100644
--- a/xen/arch/x86/hvm/stdvga.c
+++ b/xen/arch/x86/hvm/stdvga.c
@@ -322,7 +322,7 @@ static int stdvga_mem_read(const struct hvm_io_handler *handler,
data = stdvga_mem_readb(addr);
data |= stdvga_mem_readb(addr + 1) << 8;
data |= stdvga_mem_readb(addr + 2) << 16;
- data |= stdvga_mem_readb(addr + 3) << 24;
+ data |= (uint32_t)stdvga_mem_readb(addr + 3) << 24;
break;
case 8:
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] x86/hvm: Fix shifting in stdvga_mem_read()
2020-05-16 19:02 [PATCH] x86/hvm: Fix shifting in stdvga_mem_read() Andrew Cooper
@ 2020-05-18 11:11 ` Jan Beulich
0 siblings, 0 replies; 2+ messages in thread
From: Jan Beulich @ 2020-05-18 11:11 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Xen-devel, Wei Liu, Roger Pau Monné
On 16.05.2020 21:02, Andrew Cooper wrote:
> stdvga_mem_read() has a return type of uint8_t, which promotes to int rather
> than unsigned int. Shifting by 24 may hit the sign bit.
>
> Spotted by Coverity.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-05-16 19:02 [PATCH] x86/hvm: Fix shifting in stdvga_mem_read() Andrew Cooper
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