From: Mimi Zohar <zohar@linux.ibm.com>
Date: Mon, 26 Apr 2021 22:13:45 +0000 (-0400)
Subject: evm: fix writing <securityfs>/evm overflow
X-Git-Tag: v4.19.198~320
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8657d0d57d6df9d6d04277c18889da2804164ca3;p=thirdparty%2Fkernel%2Fstable.git

evm: fix writing <securityfs>/evm overflow

[ 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@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c
index 7024b14831e3d..c5c44203a59c3 100644
--- a/security/integrity/evm/evm_secfs.c
+++ b/security/integrity/evm/evm_secfs.c
@@ -71,12 +71,13 @@ 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;