From 2b9ac0b84c2cae91bbaceab62df4de6d503421ec Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 31 Jul 2024 20:37:55 +0530 Subject: virt: sev-guest: Ensure the SNP guest messages do not exceed a page Currently, struct snp_guest_msg includes a message header (96 bytes) and a payload (4000 bytes). There is an implicit assumption here that the SNP message header will always be 96 bytes, and with that assumption the payload array size has been set to 4000 bytes - a magic number. If any new member is added to the SNP message header, the SNP guest message will span more than a page. Instead of using a magic number for the payload, declare struct snp_guest_msg in a way that payload plus the message header do not exceed a page. [ bp: Massage. ] Suggested-by: Tom Lendacky Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Acked-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240731150811.156771-5-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/virt/coco') diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 3b76cbf78f41..89754b019be2 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -1092,6 +1092,8 @@ static int __init sev_guest_probe(struct platform_device *pdev) void __iomem *mapping; int ret; + BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; -- cgit v1.2.3