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Message-ID: <20220802185346.GS7074@brightrain.aerifal.cx>
Date: Tue, 2 Aug 2022 14:53:46 -0400
From: Rich Felker <dalias@...c.org>
To: Tudor Cretu <tudor.cretu@....com>
Cc: musl@...ts.openwall.com
Subject: Re: [PATCH] clone: Return EINVAL for null stack
On Tue, Aug 02, 2022 at 12:30:36PM +0100, Tudor Cretu wrote:
> This change aligns the clone wrapper with the man page. If the stack is
> null, clone sets errno to EINVAL, instead of throwing a segmentation fault.
> ---
> src/linux/clone.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/src/linux/clone.c b/src/linux/clone.c
> index 8c1af7d3..43a6803b 100644
> --- a/src/linux/clone.c
> +++ b/src/linux/clone.c
> @@ -1,4 +1,5 @@
> #define _GNU_SOURCE
> +#include <errno.h>
> #include <stdarg.h>
> #include <unistd.h>
> #include <sched.h>
> @@ -11,6 +12,10 @@ int clone(int (*func)(void *), void *stack, int flags, void *arg, ...)
> pid_t *ptid, *ctid;
> void *tls;
>
> + if (!stack) {
> + return __syscall_ret(-EINVAL);
> + }
> +
> va_start(ap, arg);
> ptid = va_arg(ap, pid_t *);
> tls = va_arg(ap, void *);
> --
> 2.25.1
This is probably okay, but there's also a bigger discussion to be had
here about what to do about clone() -- deciding what the contract is
for what usage can be supported, and possibly making the rest produce
errors like the above. There's also a matter of the current very-wrong
use of va_arg for variadic arguments that might not exist, and which
probably *can't* exist in any valid application usage. This came up
before as part of the mt-fork work, but was basically deferred
indefinitely...
Rich
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