linux-kernel - [PATCH 5.12 267/384] s390/archrandom: add parameter check for s390_arch_random

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 10 May 2021 12:20:56 +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, Sven Schnelle <svens@...ux.ibm.com>,
        Harald Freudenberger <freude@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 267/384] s390/archrandom: add parameter check for s390_arch_random_generate

From: Harald Freudenberger <freude@...ux.ibm.com>

[ Upstream commit 28096067686c5a5cbd4c35b079749bd805df5010 ]

A review of the code showed, that this function which is exposed
within the whole kernel should do a parameter check for the
amount of bytes requested. If this requested bytes is too high
an unsigned int overflow could happen causing this function to
try to memcpy a really big memory chunk.

This is not a security issue as there are only two invocations
of this function from arch/s390/include/asm/archrandom.h and both
are not exposed to userland.

Reported-by: Sven Schnelle <svens@...ux.ibm.com>
Signed-off-by: Harald Freudenberger <freude@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/s390/crypto/arch_random.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/s390/crypto/arch_random.c b/arch/s390/crypto/arch_random.c
index 7b947728d57e..56007c763902 100644
--- a/arch/s390/crypto/arch_random.c
+++ b/arch/s390/crypto/arch_random.c
@@ -54,6 +54,10 @@ static DECLARE_DELAYED_WORK(arch_rng_work, arch_rng_refill_buffer);
 
 bool s390_arch_random_generate(u8 *buf, unsigned int nbytes)
 {
+	/* max hunk is ARCH_RNG_BUF_SIZE */
+	if (nbytes > ARCH_RNG_BUF_SIZE)
+		return false;
+
 	/* lock rng buffer */
 	if (!spin_trylock(&arch_rng_lock))
 		return false;
-- 
2.30.2