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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_register_cpudef_type().

Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180109154519.25634-2-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Eduardo Habkost 2018-01-09 13:45:13 -02:00
parent c68bcb3a99
commit 807e9869b8
1 changed files with 8 additions and 1 deletions
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9
target/i386/cpu.c
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@ -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);