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Re: [PATCH] Fix writes past the allocated array bounds in execvpe (BZ# 20847)
On 21/11/2016 12:17, Andreas Schwab wrote:
> On Nov 21 2016, Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
>
>> For first issue I see so, since it allocates the argument list as:
>>
>> 64 /* Count the arguments. */
>> 65 int argc = 0;
>> 66 while (argv[argc++])
>> 67 ;
>> 68 size_t len = (argc + 1) * sizeof (char *);
>> 69 char **script_argv;
>> 70 void *ptr = NULL;
>> 71 if (__libc_use_alloca (len))
>> 72 script_argv = alloca (len);
>> 73 else
>> 74 script_argv = ptr = malloc (len);
>>
>> Taking in consideration only argument list plus one but then writing
>> argument list plus 2 position on 'scripts_argv'.
>
> But the old scripts_argv never writes to new_argv[argc+1]. Here, argc
> is already including the NULL in the old argv, and scripts_argv only has
> to prepend one new argument (and replace the old argv[0]).
Right, but then I think it incur in another issue where the resulting new
argument variable would not contain a final NULL.