From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen Gang Subject: [PATCH v2] target-ppc: kvm: Fix memory overflow issue about strncat() Date: Wed, 15 Oct 2014 21:48:07 +0800 Message-ID: <543E7B17.1050902@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: qemu-ppc@nongnu.org, kvm@vger.kernel.org, qemu-devel To: agraf@suse.de, Paolo Bonzini Return-path: Received: from mail-pa0-f50.google.com ([209.85.220.50]:54626 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751106AbaJONsW (ORCPT ); Wed, 15 Oct 2014 09:48:22 -0400 Received: by mail-pa0-f50.google.com with SMTP id kx10so1354003pab.9 for ; Wed, 15 Oct 2014 06:48:22 -0700 (PDT) Sender: kvm-owner@vger.kernel.org List-ID: strncat() will append additional '\0' to destination buffer, so need additional 1 byte for it, or may cause memory overflow, just like other area within QEMU have done. And can use g_strdup_printf() instead of strncat(), which may be more easier understanding. Signed-off-by: Chen Gang --- target-ppc/kvm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index 66e7ce5..cea6a87 100644 --- a/target-ppc/kvm.c +++ b/target-ppc/kvm.c @@ -1782,7 +1782,7 @@ static int kvmppc_find_cpu_dt(char *buf, int buf_len) * format) */ static uint64_t kvmppc_read_int_cpu_dt(const char *propname) { - char buf[PATH_MAX]; + char buf[PATH_MAX], *tmp; union { uint32_t v32; uint64_t v64; @@ -1794,10 +1794,10 @@ static uint64_t kvmppc_read_int_cpu_dt(const char *propname) return -1; } - strncat(buf, "/", sizeof(buf) - strlen(buf)); - strncat(buf, propname, sizeof(buf) - strlen(buf)); + tmp = g_strdup_printf("%s/%s", buf, propname); - f = fopen(buf, "rb"); + f = fopen(tmp, "rb"); + g_free(tmp); if (!f) { return -1; } -- 1.9.3 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48612) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XeOwd-0001km-94 for qemu-devel@nongnu.org; Wed, 15 Oct 2014 09:49:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XeOwU-0007AC-7x for qemu-devel@nongnu.org; Wed, 15 Oct 2014 09:48:51 -0400 Message-ID: <543E7B17.1050902@gmail.com> Date: Wed, 15 Oct 2014 21:48:07 +0800 From: Chen Gang MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PATCH v2] target-ppc: kvm: Fix memory overflow issue about strncat() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: agraf@suse.de, Paolo Bonzini Cc: qemu-ppc@nongnu.org, qemu-devel , kvm@vger.kernel.org strncat() will append additional '\0' to destination buffer, so need additional 1 byte for it, or may cause memory overflow, just like other area within QEMU have done. And can use g_strdup_printf() instead of strncat(), which may be more easier understanding. Signed-off-by: Chen Gang --- target-ppc/kvm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c index 66e7ce5..cea6a87 100644 --- a/target-ppc/kvm.c +++ b/target-ppc/kvm.c @@ -1782,7 +1782,7 @@ static int kvmppc_find_cpu_dt(char *buf, int buf_len) * format) */ static uint64_t kvmppc_read_int_cpu_dt(const char *propname) { - char buf[PATH_MAX]; + char buf[PATH_MAX], *tmp; union { uint32_t v32; uint64_t v64; @@ -1794,10 +1794,10 @@ static uint64_t kvmppc_read_int_cpu_dt(const char *propname) return -1; } - strncat(buf, "/", sizeof(buf) - strlen(buf)); - strncat(buf, propname, sizeof(buf) - strlen(buf)); + tmp = g_strdup_printf("%s/%s", buf, propname); - f = fopen(buf, "rb"); + f = fopen(tmp, "rb"); + g_free(tmp); if (!f) { return -1; } -- 1.9.3