From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43398) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebzWw-0002O4-QD for qemu-devel@nongnu.org; Wed, 17 Jan 2018 21:02:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ebzWu-0003uu-VP for qemu-devel@nongnu.org; Wed, 17 Jan 2018 21:02:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37450) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ebzWu-0003to-Kv for qemu-devel@nongnu.org; Wed, 17 Jan 2018 21:02:12 -0500 From: Eduardo Habkost Date: Thu, 18 Jan 2018 00:01:52 -0200 Message-Id: <20180118020157.25401-4-ehabkost@redhat.com> In-Reply-To: <20180118020157.25401-1-ehabkost@redhat.com> References: <20180118020157.25401-1-ehabkost@redhat.com> Subject: [Qemu-devel] [PULL 3/8] i386: Change X86CPUDefinition::model_id to const char* List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Paolo Bonzini , Richard Henderson , qemu-devel@nongnu.org It is valid to have a 48-character model ID on CPUID, however the definition of X86CPUDefinition::model_id is char[48], which can make the compiler drop the null terminator from the string. If a CPU model happens to have 48 bytes on model_id, "-cpu help" will print garbage and the object_property_set_str() call at x86_cpu_load_def() will read data outside the model_id array. We could increase the array size to 49, but this would mean the compiler would not issue a warning if a 49-char string is used by mistake for model_id. To make things simpler, simply change model_id to be const char*, and validate the string length using an assert() on x86_register_cpudef_type(). Reported-by: "Dr. David Alan Gilbert" Signed-off-by: Eduardo Habkost Message-Id: <20180109154519.25634-2-ehabkost@redhat.com> Signed-off-by: Eduardo Habkost --- target/i386/cpu.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 4385853646..0e26fa4ea7 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -754,7 +754,7 @@ struct X86CPUDefinition { int model; int stepping; FeatureWordArray features; - char model_id[48]; + const char *model_id; }; static X86CPUDefinition builtin_x86_defs[] = { @@ -923,6 +923,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = I486_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "pentium", @@ -934,6 +935,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = PENTIUM_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "pentium2", @@ -945,6 +947,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = PENTIUM2_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "pentium3", @@ -956,6 +959,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = PENTIUM3_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "athlon", @@ -2736,6 +2740,9 @@ static void x86_register_cpudef_type(X86CPUDefinition *def) * they shouldn't be set on the CPU model table. */ assert(!(def->features[FEAT_8000_0001_EDX] & CPUID_EXT2_AMD_ALIASES)); + /* catch mistakes instead of silently truncating model_id when too long */ + assert(def->model_id && strlen(def->model_id) <= 48); + type_register(&ti); g_free(typename); -- 2.14.3