Re: [fs/exec] 80bd5afdd8: xfstests.generic.633.fail

Christian Brauner
2022-01-31T15:37:18Z

On Mon, Jan 31, 2022 at 03:19:22PM +0000, Matthew Wilcox wrote:
> On Mon, Jan 31, 2022 at 04:08:19PM +0100, Christian Brauner wrote:
> > On Mon, Jan 31, 2022 at 10:43:52PM +0800, kernel test robot wrote:
> > I can fix this rather simply in our upstream fstests with:
> >
> > static char *argv[] = {
> > "",
> > };
> >
> > I guess.
> >
> > But doesn't
> >
> > static char *argv[] = {
> > NULL,
> > };
> >
> > seem something that should work especially with execveat()?
>
> The problem is that the exec'ed program sees an argc of 0, which is the
> problem we're trying to work around in the kernel (instead of leaving
> it to ld.so to fix for suid programs).

Ok, just seems a bit more intuitive for path-based exec than for
fd-based execveat().

What's argv[0] supposed to contain in these cases?

1. execveat(fd, NULL, ..., AT_EMPTY_PATH)
2. execveat(fd, "my-file", ..., )

"" in both 1. and 2.?
"" in 1. and "my-file" in 2.?