From: Kees Cook <keescook@chromium.org>
To: Peter Huewe <peterhuewe@gmx.de>
Cc: Kees Cook <keescook@chromium.org>,
Jarkko Sakkinen <jarkko@kernel.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
linux-integrity@vger.kernel.org,
Stefan Berger <stefanb@linux.ibm.com>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH v2] tpm: vtpm_proxy: Double-check to avoid buffer overflow
Date: Tue, 18 Jan 2022 10:36:50 -0800 [thread overview]
Message-ID: <20220118183650.3386989-1-keescook@chromium.org> (raw)
When building with -Warray-bounds, this warning was emitted:
In function 'memset',
inlined from 'vtpm_proxy_fops_read' at drivers/char/tpm/tpm_vtpm_proxy.c:102:2:
./include/linux/fortify-string.h:43:33: warning: '__builtin_memset' pointer overflow between offset 164 and size [2147483648, 4294967295]
[-Warray-bounds]
43 | #define __underlying_memset __builtin_memset
| ^
There was no checking of the req_len value. To keep this code robust,
and to silence the compiler warning, check the size before attempting
a memset().
Cc: Peter Huewe <peterhuewe@gmx.de>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-integrity@vger.kernel.org
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Link: https://lore.kernel.org/lkml/4b59d305-6858-1514-751a-37853ad777be@linux.ibm.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v1: https://lore.kernel.org/lkml/20220113002727.3709495-1-keescook@chromium.org
v2: make commit log more accurate, add Reviewed-by
---
drivers/char/tpm/tpm_vtpm_proxy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index 91c772e38bb5..5c865987ba5c 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -91,7 +91,7 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
len = proxy_dev->req_len;
- if (count < len) {
+ if (count < len || len > sizeof(proxy_dev->buffer)) {
mutex_unlock(&proxy_dev->buf_lock);
pr_debug("Invalid size in recv: count=%zd, req_len=%zd\n",
count, len);
--
2.30.2
next reply other threads:[~2022-01-18 18:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-18 18:36 Kees Cook [this message]
2022-01-18 19:32 ` [PATCH v2] tpm: vtpm_proxy: Double-check to avoid buffer overflow Jann Horn
2022-01-18 19:39 ` Jason Gunthorpe
2022-01-18 21:20 ` Kees Cook
2022-01-18 23:33 ` Jason Gunthorpe
2022-01-19 0:42 ` Jann Horn
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