linux-kernel - [PATCH 05/10] ptp: Use free_decrypted

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Date:   Tue, 17 Oct 2023 13:25:00 -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,
        Richard Cochran <richardcochran@...il.com>,
        netdev@...r.kernel.org
Subject: [PATCH 05/10] ptp: 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.

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

Cc: Richard Cochran <richardcochran@...il.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
---
 drivers/ptp/ptp_kvm_x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ptp/ptp_kvm_x86.c b/drivers/ptp/ptp_kvm_x86.c
index 902844cc1a17..203af060013d 100644
--- a/drivers/ptp/ptp_kvm_x86.c
+++ b/drivers/ptp/ptp_kvm_x86.c
@@ -36,7 +36,7 @@ int kvm_arch_ptp_init(void)
 		clock_pair = page_address(p);
 		ret = set_memory_decrypted((unsigned long)clock_pair, 1);
 		if (ret) {
-			__free_page(p);
+			free_decrypted_pages((unsigned long)clock_pair, 0);
 			clock_pair = NULL;
 			goto nofree;
 		}
-- 
2.34.1