From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Tue, 9 Jan 2018 13:45:13 -0200 Subject: [PATCH] i386: Change X86CPUDefinition::model_id to const char* 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_cpu_cpudef_class_init. Reported-by: "Dr. David Alan Gilbert" 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 3d53cb4c86..c673521016 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -753,7 +753,7 @@ struct X86CPUDefinition { int model; int stepping; FeatureWordArray features; - char model_id[48]; + const char *model_id; }; static X86CPUDefinition builtin_x86_defs[] = { @@ -922,6 +922,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = I486_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "pentium", @@ -933,6 +934,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = PENTIUM_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "pentium2", @@ -944,6 +946,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = PENTIUM2_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "pentium3", @@ -955,6 +958,7 @@ static X86CPUDefinition builtin_x86_defs[] = { .features[FEAT_1_EDX] = PENTIUM3_FEATURES, .xlevel = 0, + .model_id = "", }, { .name = "athlon", @@ -2617,6 +2621,9 @@ 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); -- 2.11.0