[xen stable-4.20] x86/cpu: Validate CPUID leaf 0x2 EDX output

[patchbot@xxxxxxx]

commit 2bd2c08a0f63d60bc1f8cc69ec9677d39f66aecf
Author:     Ahmed S. Darwish <darwi@xxxxxxxxxxxxx>
AuthorDate: Tue Apr 29 11:41:13 2025 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 29 11:41:13 2025 +0200

    x86/cpu: Validate CPUID leaf 0x2 EDX output
    
    CPUID leaf 0x2 emits one-byte descriptors in its four output registers
    EAX, EBX, ECX, and EDX.  For these descriptors to be valid, the most
    significant bit (MSB) of each register must be clear.
    
    Leaf 0x2 parsing at intel.c only validated the MSBs of EAX, EBX, and
    ECX, but left EDX unchecked.
    
    Validate EDX's most-significant bit as well.
    
    Fixes: 1aa6feb63bfd ("Port CPU setup code from Linux 2.6")
    Signed-off-by: Ahmed S. Darwish <darwi@xxxxxxxxxxxxx>
    Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20250304085152.51092-3-darwi@xxxxxxxxxxxxx
    
    Use ARRAY_SIZE() though.
    
    Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
1881148215c6
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: a47b44a8f0a58a6015faf6465921cd203f0b51d1
    master date: 2025-04-08 09:37:38 +0200
---
 xen/arch/x86/cpu/intel_cacheinfo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/cpu/intel_cacheinfo.c 
b/xen/arch/x86/cpu/intel_cacheinfo.c
index 9cfb759be0..e88faa7545 100644
--- a/xen/arch/x86/cpu/intel_cacheinfo.c
+++ b/xen/arch/x86/cpu/intel_cacheinfo.c
@@ -186,7 +186,7 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c)
                        cpuid(2, &regs[0], &regs[1], &regs[2], &regs[3]);
 
                        /* If bit 31 is set, this is an unknown format */
-                       for ( j = 0 ; j < 3 ; j++ ) {
+                       for ( j = 0; j < ARRAY_SIZE(regs); j++ ) {
                                if ( regs[j] >> 31 )
                                        regs[j] = 0;
                        }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.20