linux-kernel - Re: [PATCH v5 2/4] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations

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Date:   Fri, 8 Jun 2018 16:03:55 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
        "Du, Changbin" <changbin.du@...el.com>, gregkh@...uxfoundation.org,
        alex.elder@...aro.org, kbuild test robot <lkp@...el.com>,
        linux-arch@...r.kernel.org, michal.lkml@...kovi.net,
        linux-kernel@...r.kernel.org, arnd@...db.de,
        yamada.masahiro@...ionext.com, lgirdwood@...il.com,
        broonie@...nel.org, rdunlap@...radead.org, x86@...nel.org,
        linux@...linux.org.uk, linux-sparse@...r.kernel.org,
        mingo@...hat.com, kbuild-all@...org, akpm@...ux-foundation.org,
        changbin.du@...il.com, tglx@...utronix.de,
        linux-kbuild@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 2/4] kernel hacking: new config NO_AUTO_INLINE to
 disable compiler auto-inline optimizations

On Thu, 7 Jun 2018 11:18:16 +0200
Johan Hovold <johan@...nel.org> wrote:


> If you want to work around the warning and think you can do it in some
> non-contrived way, then go for it.
> 
> Clearing the request buffer, checking for termination using strnlen, and
> then using memcpy might not be too bad.
> 
> But after all, it is a false positive, so leaving things as they stand
> is fine too.

Not sure how contrived you think this is, but it solves the warning
without adding extra work in the normal case.

-- Steve

diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c
index 71aec14f8181..4fb9f1dff47d 100644
--- a/drivers/staging/greybus/fw-management.c
+++ b/drivers/staging/greybus/fw-management.c
@@ -150,15 +150,18 @@ static int fw_mgmt_load_and_validate_operation(struct fw_mgmt *fw_mgmt,
 	}
 
 	request.load_method = load_method;
-	strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);
+	strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE - 1);
 
 	/*
 	 * The firmware-tag should be NULL terminated, otherwise throw error and
 	 * fail.
 	 */
-	if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') {
-		dev_err(fw_mgmt->parent, "load-and-validate: firmware-tag is not NULL terminated\n");
-		return -EINVAL;
+	if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 2] != '\0') {
+		if (tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') {
+			dev_err(fw_mgmt->parent, "load-and-validate: firmware-tag is not NULL terminated\n");
+			return -EINVAL;
+		}
+		request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] = '\0';
 	}
 
 	/* Allocate ids from 1 to 255 (u8-max), 0 is an invalid id */