linux-kernel - [tip: x86/urgent] x86/sgx: Fix size overflows in sgx_encl

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Message-ID: <174116554044.14745.885486771542250636.tip-bot2@tip-bot2>
Date: Wed, 05 Mar 2025 09:05:40 -0000
From: "tip-bot2 for Jarkko Sakkinen" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Dan Carpenter <dan.carpenter@...aro.org>,
 Jarkko Sakkinen <jarkko@...nel.org>, Ingo Molnar <mingo@...nel.org>,
 Dave Hansen <dave.hansen@...el.com>, Peter Zijlstra <peterz@...radead.org>,
 "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/sgx: Fix size overflows in sgx_encl_create()

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

Commit-ID:     0d3e0dfd68fb9e6b0ec865be9f3377cc3ff55733
Gitweb:        https://git.kernel.org/tip/0d3e0dfd68fb9e6b0ec865be9f3377cc3ff55733
Author:        Jarkko Sakkinen <jarkko@...nel.org>
AuthorDate:    Wed, 05 Mar 2025 07:00:05 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 05 Mar 2025 09:51:41 +01:00

x86/sgx: Fix size overflows in sgx_encl_create()

The total size calculated for EPC can overflow u64 given the added up page
for SECS.  Further, the total size calculated for shmem can overflow even
when the EPC size stays within limits of u64, given that it adds the extra
space for 128 byte PCMD structures (one for each page).

Address this by pre-evaluating the micro-architectural requirement of
SGX: the address space size must be power of two. This is eventually
checked up by ECREATE but the pre-check has the additional benefit of
making sure that there is some space for additional data.

Fixes: 888d24911787 ("x86/sgx: Add SGX_IOC_ENCLAVE_CREATE")
Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Dave Hansen <dave.hansen@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: "H. Peter Anvin" <hpa@...or.com>
Link: https://lore.kernel.org/r/20250305050006.43896-1-jarkko@kernel.org

Closes: https://lore.kernel.org/linux-sgx/c87e01a0-e7dd-4749-a348-0980d3444f04@stanley.mountain/
---
 arch/x86/kernel/cpu/sgx/ioctl.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index b65ab21..776a201 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -64,6 +64,13 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
 	struct file *backing;
 	long ret;

+	/*
+	 * ECREATE would detect this too, but checking here also ensures
+	 * that the 'encl_size' calculations below can never overflow.
+	 */
+	if (!is_power_of_2(secs->size))
+		return -EINVAL;
+
 	va_page = sgx_encl_grow(encl, true);
 	if (IS_ERR(va_page))
 		return PTR_ERR(va_page);