Re: [Qemu-devel] [PATCH] qemu-io: initialize progname with error_set_progname()

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Mon, Aug 11, 2014 at 03:50:03PM +0900, Hitoshi Mitake wrote:
> Calling error_get_progname() in the context of qemu-io can cause
> segmentation fault because qemu-io doesn't initialize its progname
> with error_set_progname(). This patch adds the initialization.
> 
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
> ---
>  qemu-io.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/qemu-io.c b/qemu-io.c
> index b55a550..6f08a91 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -395,6 +395,7 @@ int main(int argc, char **argv)
>  #endif
>  
>      progname = basename(argv[0]);
> +    error_set_progname(progname);

From the basename(3) man page:

  These  functions  may return pointers to statically allocated memory which may be overwritten by subsequent calls.

Since error_set_progname() does not copy its argument, it is not safe to
pass the basename(3) return value.  Just pass in argv[0] like vl.c does.

Please also update the commit description to make it clear that
qemu-io currently does not use error_get_progname() so the crash doesn't
occur in practice (I guess you discovered it while modifying the code).

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