[xen stable-4.12] x86/hvm: Fix shifting in stdvga_mem_read()

[patchbot@xxxxxxx]

commit f769c99f923d0bba81626f4b50bb1e2ebc5ec9b9
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Jun 24 17:00:33 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jun 24 17:00:33 2020 +0200

    x86/hvm: Fix shifting in stdvga_mem_read()
    
    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@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 97fb0253e6c2f2221bfd0895b7ffe3a99330d847
    master date: 2020-05-18 15:22:53 +0100
---
 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:
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12