Re: [PATCH 2/2] Fix stack-use-after-scope error reported by ASAN by GCC 7.

From: Jeff King <peff@peff.net>
Date: Apr 6, 2017, 08:33 UTC
Message-ID: <20170406083305.bs3hkxp7dagajg7m@sigill.intra.peff.net>
In-Reply-To: <072afb58-6159-ddeb-b7dc-40a87e8c6ae7@suse.cz>

On Thu, Apr 06, 2017 at 10:02:45AM +0200, Martin Liška wrote:

Show 8 quoted lines

> Subject: [PATCH 2/2] Fix stack-use-after-scope error reported by ASAN by GCC
>  7.
> 
> The use-after-scope is triggered here:
> READ of size 8 at 0x7ffc4f674e20 thread T0
>     #0 0x6f0b69 in finish_command /home/marxin/Programming/git/run-command.c:570
>     #1 0x5b6101 in kill_multi_file_filter /home/marxin/Programming/git/convert.c:570
>     #2 0x5b798a in kill_multi_file_filter /home/marxin/Programming/git/convert.c:770

Yeah, this is definitely a problem. Your fix works, but...

Show 10 quoted lines

> @@ -600,7 +601,8 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
>  	process = &entry->process;
>  
>  	child_process_init(process);
> -	process->argv = argv;
> +	process->argv = xcalloc(2, sizeof(const char *));
> +	process->argv[0] = cmd;
>  	process->use_shell = 1;
>  	process->in = -1;
>  	process->out = -1;

We can just do:

  argv_array_push(&process->args, cmd);

here. And then it is freed automatically when finish_command() is called (and also if start_command never starts the process, which I think your patch misses).

-Peff