From patchwork Wed Dec 13 16:42:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lee Jones X-Patchwork-Id: 13491635 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0AC53A8FF for ; Wed, 13 Dec 2023 16:43:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Plg/RkoE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8150DC433C9; Wed, 13 Dec 2023 16:43:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702485794; bh=+jJ0AZEvag610YYMeIA2DZY9vRhnQ1MUWo6qd+Qzkcs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Plg/RkoEgxcb5oLFgT/r2pbwVa+OiOKfDqeFr23Y4XhEqyZ5uVBDN++Xkp9njtYA/ e/ZmXCZgAUTOyvm1+MRDRVjk/Goo8EXcyPKp/Z5Jq6vkTd7Z0kpFegYh/Cr9+MFWQC ExHTW5hlY3r+qo8ZKQSDl3P2AIFZRW2roFNhvsQBR8o6zm7rZPMr8nRhSijOrPYRQB jum+fusgZZy+M4y8zPPL3U6Btq5SJH2c8BRlGS5oiDRK4vX1rVhGb5qPcu+A+1FypL eGsgpAVmBSsoR8RBqoGoAYvcP7xcmaFTF+SCgp92suHe8vT62kPWYfSnmce8dWivHj 6fNgbUfjI7k1Q== From: Lee Jones To: lee@kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: [PATCH 09/12] usb: mon_stat: Replace snprintf() with the safer scnprintf() variant Date: Wed, 13 Dec 2023 16:42:38 +0000 Message-ID: <20231213164246.1021885-10-lee@kernel.org> X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog In-Reply-To: <20231213164246.1021885-1-lee@kernel.org> References: <20231213164246.1021885-1-lee@kernel.org> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 There is a general misunderstanding amongst engineers that {v}snprintf() returns the length of the data *actually* encoded into the destination array. However, as per the C99 standard {v}snprintf() really returns the length of the data that *would have been* written if there were enough space for it. This misunderstanding has led to buffer-overruns in the past. It's generally considered safer to use the {v}scnprintf() variants in their place (or even sprintf() in simple cases). So let's do that. Link: https://lwn.net/Articles/69419/ Link: https://github.com/KSPP/linux/issues/105 Signed-off-by: Lee Jones --- drivers/usb/mon/mon_stat.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/mon/mon_stat.c b/drivers/usb/mon/mon_stat.c index 98ab0cc473d67..3c23805ab1a44 100644 --- a/drivers/usb/mon/mon_stat.c +++ b/drivers/usb/mon/mon_stat.c @@ -35,9 +35,9 @@ static int mon_stat_open(struct inode *inode, struct file *file) mbus = inode->i_private; - sp->slen = snprintf(sp->str, STAT_BUF_SIZE, - "nreaders %d events %u text_lost %u\n", - mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost); + sp->slen = scnprintf(sp->str, STAT_BUF_SIZE, + "nreaders %d events %u text_lost %u\n", + mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost); file->private_data = sp; return 0;