LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Len Baker <len.baker@gmx.com>
To: Maxim Levitsky <maximlevitsky@gmail.com>,
	Alex Dubov <oakad@yahoo.com>,
	Ulf Hansson <ulf.hansson@linaro.org>
Cc: Len Baker <len.baker@gmx.com>, Kees Cook <keescook@chromium.org>,
	Tom Rix <trix@redhat.com>,
	linux-hardening@vger.kernel.org, linux-mmc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] memstick: jmb38x_ms: Prefer struct_size over open coded arithmetic
Date: Sat, 11 Sep 2021 15:19:33 +0200	[thread overview]
Message-ID: <20210911131933.2089-1-len.baker@gmx.com> (raw)

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kzalloc() function.

[1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/memstick/host/jmb38x_ms.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/memstick/host/jmb38x_ms.c b/drivers/memstick/host/jmb38x_ms.c
index f9a93b0565e1..a7a0f0caea15 100644
--- a/drivers/memstick/host/jmb38x_ms.c
+++ b/drivers/memstick/host/jmb38x_ms.c
@@ -927,8 +927,7 @@ static int jmb38x_ms_probe(struct pci_dev *pdev,
 		goto err_out_int;
 	}

-	jm = kzalloc(sizeof(struct jmb38x_ms)
-		     + cnt * sizeof(struct memstick_host *), GFP_KERNEL);
+	jm = kzalloc(struct_size(jm, hosts, cnt), GFP_KERNEL);
 	if (!jm) {
 		rc = -ENOMEM;
 		goto err_out_int;
--
2.25.1


             reply	other threads:[~2021-09-11 13:23 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-11 13:19 Len Baker [this message]
2021-09-14 11:23 ` Ulf Hansson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210911131933.2089-1-len.baker@gmx.com \
    --to=len.baker@gmx.com \
    --cc=keescook@chromium.org \
    --cc=linux-hardening@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mmc@vger.kernel.org \
    --cc=maximlevitsky@gmail.com \
    --cc=oakad@yahoo.com \
    --cc=trix@redhat.com \
    --cc=ulf.hansson@linaro.org \
    --subject='Re: [PATCH] memstick: jmb38x_ms: Prefer struct_size over open coded arithmetic' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).