Re: [PATCH] tests/tcg: fix buffer overflow in multiarch/linux/linux-sigrtminmax

["Alex Bennée" <alex.bennee@linaro.org>]

Markus Armbruster <armbru@redhat.com> writes:

> Max Filippov <jcmvbkbc@gmail.com> writes:
>
>> Fix new_argv allocation size to be `(argc + 2) * sizeof(char *)` bytes,
>> which matches the way it's used to store `argc + 2` pointers.
>>
>> This fixes the test for me, which otherwise fails on xtensa with the
>> following message
>>
>>   linux-sigrtminmax.c: 59: main: Assertion `execve(new_argv[0], new_argv, environ) == 0' failed.'.
>>
>> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
>> ---
>>  tests/tcg/multiarch/linux/linux-sigrtminmax.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tests/tcg/multiarch/linux/linux-sigrtminmax.c b/tests/tcg/multiarch/linux/linux-sigrtminmax.c
>> index a7059aacd9cb..b5ea65f3d393 100644
>> --- a/tests/tcg/multiarch/linux/linux-sigrtminmax.c
>> +++ b/tests/tcg/multiarch/linux/linux-sigrtminmax.c
>> @@ -39,7 +39,7 @@ int main(int argc, char **argv)
>>      assert(qemu);
>>  
>>      if (!getenv("QEMU_RTSIG_MAP")) {
>> -        char **new_argv = malloc((argc + 2) + sizeof(char *));
>> +        char **new_argv = malloc((argc + 2) * sizeof(char *));
>
> If you can switch to glib's malloc, then g_new(argc + 2, sizeof(char *))
> is better.  Yes, @argc can't become big enough for the multiplication to
> overflow, but g_new() removes the need for reasoning.

Not for TCG test cases - we are limited to plain old glibc.

>
>>          int tsig1, hsig1, count1, tsig2, hsig2, count2;
>>          char rt_sigmap[64];

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro