Linux kernel staging patches
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From: Arnd Bergmann <arnd@kernel.org>
To: linux-kernel@vger.kernel.org, Viresh Kumar <vireshk@kernel.org>,
	Johan Hovold <johan@kernel.org>, Alex Elder <elder@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	greybus-dev@lists.linaro.org, linux-staging@lists.linux.dev
Subject: [PATCH 10/11] staging: greybus: change strncpy() to strscpy()
Date: Thu, 28 Mar 2024 15:04:54 +0100	[thread overview]
Message-ID: <20240328140512.4148825-11-arnd@kernel.org> (raw)
In-Reply-To: <20240328140512.4148825-1-arnd@kernel.org>

From: Arnd Bergmann <arnd@arndb.de>

gcc-10 warns about a strncpy() that does not enforce zero-termination:

In file included from include/linux/string.h:369,
                 from drivers/staging/greybus/fw-management.c:9:
In function 'strncpy',
    inlined from 'fw_mgmt_backend_fw_update_operation' at drivers/staging/greybus/fw-management.c:306:2:
include/linux/fortify-string.h:108:30: error: '__builtin_strncpy' specified bound 10 equals destination size [-Werror=stringop-truncation]
  108 | #define __underlying_strncpy __builtin_strncpy
      |                              ^
include/linux/fortify-string.h:187:9: note: in expansion of macro '__underlying_strncpy'
  187 |  return __underlying_strncpy(p, q, size);
      |         ^~~~~~~~~~~~~~~~~~~~

For some reason, I cannot reproduce this with gcc-9 or gcc-11, so I'm not
sure what's going on. Changing it to strspy() avoids the warning. In this
case the existing check for zero-termination would fail but can be replaced
with an error check.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
This is from randconfig testing with random gcc versions, a .config to
reproduce is at https://pastebin.com/r13yezkU
---
 drivers/staging/greybus/fw-management.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/fw-management.c b/drivers/staging/greybus/fw-management.c
index 3054f084d777..35bfdd5f32d2 100644
--- a/drivers/staging/greybus/fw-management.c
+++ b/drivers/staging/greybus/fw-management.c
@@ -303,13 +303,13 @@ static int fw_mgmt_backend_fw_update_operation(struct fw_mgmt *fw_mgmt,
 	struct gb_fw_mgmt_backend_fw_update_request request;
 	int ret;
 
-	strncpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);
+	ret = strscpy(request.firmware_tag, tag, GB_FIRMWARE_TAG_MAX_SIZE);
 
 	/*
 	 * The firmware-tag should be NULL terminated, otherwise throw error and
 	 * fail.
 	 */
-	if (request.firmware_tag[GB_FIRMWARE_TAG_MAX_SIZE - 1] != '\0') {
+	if (ret == -E2BIG) {
 		dev_err(fw_mgmt->parent, "backend-update: firmware-tag is not NULL terminated\n");
 		return -EINVAL;
 	}
-- 
2.39.2


  parent reply	other threads:[~2024-03-28 14:07 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-28 14:04 [PATCH 00/11] address remaining stringop-truncation warnings Arnd Bergmann
2024-03-28 14:04 ` [PATCH 01/11] staging: vc04_services: changen strncpy() to strscpy_pad() Arnd Bergmann
2024-03-28 14:42   ` Dan Carpenter
2024-03-28 16:15     ` Arnd Bergmann
2024-03-28 23:10   ` Justin Stitt
2024-03-28 14:04 ` [PATCH 03/11] staging: replace weird strncpy() with memcpy() Arnd Bergmann
2024-03-28 16:35   ` Dan Carpenter
2024-04-08 14:45     ` Arnd Bergmann
2024-04-08 15:59       ` Dan Carpenter
2024-04-08 19:20         ` Arnd Bergmann
2024-03-28 14:04 ` [PATCH 09/11] staging: rtl8723bs: convert strncpy to strscpy Arnd Bergmann
2024-03-28 23:01   ` Justin Stitt
2024-04-08 18:15     ` Arnd Bergmann
2024-03-28 14:04 ` Arnd Bergmann [this message]
2024-03-28 15:00   ` [PATCH 10/11] staging: greybus: change strncpy() to strscpy() Dan Carpenter
2024-04-08 18:26     ` Arnd Bergmann
2024-04-09  7:09       ` Dan Carpenter
2024-03-28 23:28   ` Justin Stitt
2024-04-08 18:30     ` Arnd Bergmann

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