5.15-stable review patch. If anyone has any objections, please let me know.
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From: Ahmed S. Darwish darwi@linutronix.de
commit 8177c6bedb7013cf736137da586cf783922309dd upstream.
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.
The historical Git commit:
019361a20f016 ("- pre6: Intel: start to add Pentium IV specific stuff (128-byte cacheline etc)...")
introduced leaf 0x2 output parsing. It only validated the MSBs of EAX, EBX, and ECX, but left EDX unchecked.
Validate EDX's most-significant bit.
Signed-off-by: Ahmed S. Darwish darwi@linutronix.de Signed-off-by: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org Cc: "H. Peter Anvin" hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/20250304085152.51092-2-darwi@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/cacheinfo.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/cacheinfo.c +++ b/arch/x86/kernel/cpu/cacheinfo.c @@ -795,7 +795,7 @@ void init_intel_cacheinfo(struct cpuinfo cpuid(2, ®s[0], ®s[1], ®s[2], ®s[3]);
/* If bit 31 is set, this is an unknown format */ - for (j = 0 ; j < 3 ; j++) + for (j = 0 ; j < 4 ; j++) if (regs[j] & (1 << 31)) regs[j] = 0;