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[92.21.58.28]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b47285c4f9sm1945049f8f.88.2025.07.04.02.20.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jul 2025 02:20:27 -0700 (PDT) Date: Fri, 4 Jul 2025 10:20:07 +0100 From: David Laight To: Usman Akinyemi Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, james.clark@linaro.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev Subject: Re: [PATCH] perf/x86: Replace strncpy() with memcpy() for vendor string Message-ID: <20250704102007.6354ce9f@pumpkin> In-Reply-To: <20250618215843.109941-1-usmanakinyemi202@gmail.com> References: <20250618215843.109941-1-usmanakinyemi202@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 19 Jun 2025 03:28:43 +0530 Usman Akinyemi wrote: > strncpy() is unsafe for fixed-size binary data as > it may not NUL-terminate and is deprecated for such > usage. Since we're copying raw CPUID register values, > memcpy() is the correct and safe choice. > > Signed-off-by: Usman Akinyemi > --- > tools/perf/arch/x86/util/header.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/arch/x86/util/header.c b/tools/perf/arch/x86/util/header.c > index 412977f8aa83..43ba55627817 100644 > --- a/tools/perf/arch/x86/util/header.c > +++ b/tools/perf/arch/x86/util/header.c > @@ -16,9 +16,9 @@ void get_cpuid_0(char *vendor, unsigned int *lvl) > unsigned int b, c, d; > > cpuid(0, 0, lvl, &b, &c, &d); > - strncpy(&vendor[0], (char *)(&b), 4); > - strncpy(&vendor[4], (char *)(&d), 4); > - strncpy(&vendor[8], (char *)(&c), 4); > + memcpy(&vendor[0], (char *)(&b), 4); > + memcpy(&vendor[4], (char *)(&d), 4); > + memcpy(&vendor[8], (char *)(&c), 4); Why not: cpuid(0, 0, lvl, (void *)vendor, (void *)(vendor + 8), (void *)(vendor + 4)); > vendor[12] = '\0'; > } >