Re: [libvirt] [PATCH] x86Decode: avoid NULL-dereference upon questionable input
According to Jim Meyering on 3/1/2010 1:21 PM:
Clang warned about the potential NULL-dereference
via the STREQ/strcmp below. models[i] could be NULL.
Even "models" could be NULL, and the "allowed = ..." test
makes that appear to be deliberately allowed.
This same function was also listed by coverity, but only for models, not
models[i].
The change below is the least invasive and cleanest
I could come up with, assuming there is no need to diagnose
(e.g., by returning -1) the condition of a NULL models[i] pointer.
while (candidate != NULL) {
bool allowed = (models == NULL);
for (i = 0; i < candidate->ncpuid; i++) {
cpuid = x86DataCpuid(data, candidate->cpuid[i].function);
if (cpuid == NULL
|| !x86cpuidMatchMasked(cpuid, candidate->cpuid + i))
goto next;
}
for (i = 0; i < nmodels; i++) {
- if (STREQ(models[i], candidate->name)) {
+ if (models && models[i] && STREQ(models[i],
candidate->name)) {
Isn't the intent that (models==NULL) iff (nmodels==0)? In which case,
this code is unreachable if models is NULL. But your patch certainly is
the least-invasive possible, and while it is only a false positive for
well-formed arguments, I didn't spend time checking all clients of
x86Decode to see if there is ever a possibility of bad arguments.
ACK
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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