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Message-ID: <20170309084208.ims3ehcnieo7uqew@pd.tnic>
Date: Thu, 9 Mar 2017 09:42:08 +0100
From: Borislav Petkov <bp@...en8.de>
To: Thomas Garnier <thgarnie@...gle.com>
Cc: David Howells <dhowells@...hat.com>,
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Subject: Re: [PATCH v2 1/4] syscalls: Restore address limit after a syscall
On Wed, Mar 08, 2017 at 05:24:53PM -0800, Thomas Garnier wrote:
> @@ -191,6 +191,22 @@ extern struct trace_event_functions exit_syscall_print_funcs;
> SYSCALL_METADATA(sname, x, __VA_ARGS__) \
> __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
>
> +asmlinkage void verify_pre_usermode_state(void);
> +
> +#ifndef CONFIG_ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE
> +static inline bool has_user_ds(void) {
> + bool ret = segment_eq(get_fs(), USER_DS);
> + // Prevent re-ordering the call
This is not the kernel comments style. Use /* */ instead.
> + barrier();
> + return ret;
> +}
> +#else
> +static inline bool has_user_ds(void) {
> + return false;
> +}
> +#endif
... and then you could slim down the ifdeffery a bit:
static inline bool has_user_ds(void) {
bool ret = false;
#ifndef CONFIG_ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE
ret = segment_eq(get_fs(), USER_DS);
/* Prevent re-ordering the call. */
barrier();
#endif
return ret;
}
--
Regards/Gruss,
Boris.
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