From 57bc6e40e82c0446a358ab01f9bbf0db0d9465e4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Fri, 11 Nov 2022 13:45:50 +0100 Subject: [PATCH] libvduse: Avoid warning about dangerous use of strncpy() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit GCC 8 added a -Wstringop-truncation warning: The -Wstringop-truncation warning added in GCC 8.0 via r254630 for bug 81117 is specifically intended to highlight likely unintended uses of the strncpy function that truncate the terminating NUL character from the source string. Here the next line indeed unconditionally zeroes the last byte, but 1/ the buffer has been calloc'd, so we don't need to add an extra byte, and 2/ we called vduse_name_is_invalid() which checked the string length, so we can simply call strcpy(). This fixes when using gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0: [42/666] Compiling C object subprojects/libvduse/libvduse.a.p/libvduse.c.o FAILED: subprojects/libvduse/libvduse.a.p/libvduse.c.o cc -m64 -mcx16 -Isubprojects/libvduse/libvduse.a.p -Isubprojects/libvduse -I../../subprojects/libvduse [...] -o subprojects/libvduse/libvduse.a.p/libvduse.c.o -c ../../subprojects/libvduse/libvduse.c In file included from /usr/include/string.h:495, from ../../subprojects/libvduse/libvduse.c:24: In function ‘strncpy’, inlined from ‘vduse_dev_create’ at ../../subprojects/libvduse/libvduse.c:1312:5: /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 256 equals destination size [-Werror=stringop-truncation] 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors ninja: build stopped: cannot make progress due to previous errors. Fixes: d9cf16c0be ("libvduse: Replace strcpy() with strncpy()") Suggested-by: Markus Armbruster Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Xie Yongji Reviewed-by: Stefan Hajnoczi Tested-by: Bin Meng Signed-off-by: Stefan Hajnoczi Message-Id: <20221111124550.35753-1-philmd@linaro.org> --- subprojects/libvduse/libvduse.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/subprojects/libvduse/libvduse.c b/subprojects/libvduse/libvduse.c index 1a5981445c..e089d4d546 100644 --- a/subprojects/libvduse/libvduse.c +++ b/subprojects/libvduse/libvduse.c @@ -1309,8 +1309,8 @@ VduseDev *vduse_dev_create(const char *name, uint32_t device_id, goto err_dev; } - strncpy(dev_config->name, name, VDUSE_NAME_MAX); - dev_config->name[VDUSE_NAME_MAX - 1] = '\0'; + assert(!vduse_name_is_invalid(name)); + strcpy(dev_config->name, name); dev_config->device_id = device_id; dev_config->vendor_id = vendor_id; dev_config->features = features;