linux-kernel - [PATCH 5.12 264/700] evm: fix writing <securityfs>/evm overflow

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Message-Id: <20210712061004.287297169@linuxfoundation.org>
Date:   Mon, 12 Jul 2021 08:05:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mimi Zohar <zohar@...ux.ibm.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 264/700] evm: fix writing <securityfs>/evm overflow

From: Mimi Zohar <zohar@...ux.ibm.com>

[ Upstream commit 49219d9b8785ba712575c40e48ce0f7461254626 ]

EVM_SETUP_COMPLETE is defined as 0x80000000, which is larger than INT_MAX.
The "-fno-strict-overflow" compiler option properly prevents signaling
EVM that the EVM policy setup is complete.  Define and read an unsigned
int.

Fixes: f00d79750712 ("EVM: Allow userspace to signal an RSA key has been loaded")
Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 security/integrity/evm/evm_secfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c
index c175e2b659e4..5f0da41bccd0 100644
--- a/security/integrity/evm/evm_secfs.c
+++ b/security/integrity/evm/evm_secfs.c
@@ -66,12 +66,13 @@ static ssize_t evm_read_key(struct file *filp, char __user *buf,
 static ssize_t evm_write_key(struct file *file, const char __user *buf,
 			     size_t count, loff_t *ppos)
 {
-	int i, ret;
+	unsigned int i;
+	int ret;
 
 	if (!capable(CAP_SYS_ADMIN) || (evm_initialized & EVM_SETUP_COMPLETE))
 		return -EPERM;
 
-	ret = kstrtoint_from_user(buf, count, 0, &i);
+	ret = kstrtouint_from_user(buf, count, 0, &i);
 
 	if (ret)
 		return ret;
-- 
2.30.2