linux-kernel - [PATCH 03/10] kvmclock: Use free_decrypted

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Message-Id: <20231017202505.340906-4-rick.p.edgecombe@intel.com>
Date:   Tue, 17 Oct 2023 13:24:58 -0700
From:   Rick Edgecombe <rick.p.edgecombe@...el.com>
To:     x86@...nel.org, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, luto@...nel.org,
        peterz@...radead.org, kirill.shutemov@...ux.intel.com,
        elena.reshetova@...el.com, isaku.yamahata@...el.com,
        seanjc@...gle.com, Michael Kelley <mikelley@...rosoft.com>,
        thomas.lendacky@....com, decui@...rosoft.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Cc:     rick.p.edgecombe@...el.com, Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Subject: [PATCH 03/10] kvmclock: Use free_decrypted_pages()

On TDX it is possible for the untrusted host to cause
set_memory_encrypted() or set_memory_decrypted() to fail such that an
error is returned and the resulting memory is shared. Callers need to take
care to handle these errors to avoid returning decrypted (shared) memory to
the page allocator, which could lead to functional or security issues.

Kvmclock could free decrypted/shared pages if set_memory_decrypted() fails.
Use the recently added free_decrypted_pages() to avoid this.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Wanpeng Li <wanpengli@...cent.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
---
 arch/x86/kernel/kvmclock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index fb8f52149be9..587b159c4e53 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -227,7 +227,7 @@ static void __init kvmclock_init_mem(void)
 		r = set_memory_decrypted((unsigned long) hvclock_mem,
 					 1UL << order);
 		if (r) {
-			__free_pages(p, order);
+			free_decrypted_pages((unsigned long)hvclock_mem, order);
 			hvclock_mem = NULL;
 			pr_warn("kvmclock: set_memory_decrypted() failed. Disabling\n");
 			return;
-- 
2.34.1