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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Wei Liu" <wl@xen.org>, "Jan Beulich" <JBeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [PATCH] x86/hvm: Fix shifting in stdvga_mem_read()
Date: Sat, 16 May 2020 20:02:11 +0100	[thread overview]
Message-ID: <20200516190211.4120-1-andrew.cooper3@citrix.com> (raw)

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



             reply	other threads:[~2020-05-16 19:03 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-16 19:02 Andrew Cooper [this message]
2020-05-18 11:11 ` [PATCH] x86/hvm: Fix shifting in stdvga_mem_read() Jan Beulich

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