linux-kernel - [PATCH] x86/sev: Change npages to unsigned long in snp_accept

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Message-ID: <6d511c25576494f682063c9fb6c705b526a3757e.1687441505.git.thomas.lendacky@amd.com>
Date:   Thu, 22 Jun 2023 08:45:05 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Michael Roth <michael.roth@....com>,
        Ashish Kalra <ashish.kalra@....com>
Subject: [PATCH] x86/sev: Change npages to unsigned long in snp_accept_memory()

In snp_accept_memory(), the npages variables value is calculated from
phys_addr_t variables but is an unsigned int. A very large range passed
into snp_accept_memory() could lead to truncating npages to zero.

Fixes: 6c3211796326 ("x86/sev: Add SNP-specific unaccepted memory support")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/sev.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 1ee7bed453de..2b0342a03c1b 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -868,8 +868,7 @@ void snp_set_memory_private(unsigned long vaddr, unsigned long npages)
 
 void snp_accept_memory(phys_addr_t start, phys_addr_t end)
 {
-	unsigned long vaddr;
-	unsigned int npages;
+	unsigned long vaddr, npages;
 
 	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
 		return;
-- 
2.40.1