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

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Date:   Wed, 04 Oct 2023 09:50:10 -0000
From:   "tip-bot2 for Tom Lendacky" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        "Borislav Petkov (AMD)" <bp@...en8.de>, <stable@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/sev: Change npages to unsigned long in
 snp_accept_memory()

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     62d5e970d022ef4bde18948dd67247c3194384c1
Gitweb:        https://git.kernel.org/tip/62d5e970d022ef4bde18948dd67247c3194384c1
Author:        Tom Lendacky <thomas.lendacky@....com>
AuthorDate:    Thu, 22 Jun 2023 08:45:05 -05:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 02 Oct 2023 14:55:41 +02:00

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. This
doesn't happen at the moment but let's be prepared.

Fixes: 6c3211796326 ("x86/sev: Add SNP-specific unaccepted memory support")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Cc: <stable@...nel.org>
Link: https://lore.kernel.org/r/6d511c25576494f682063c9fb6c705b526a3757e.1687441505.git.thomas.lendacky@amd.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 2787826..d8c1e3b 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;