On Thu, 2021-11-11 at 19:57 +0100, Jan Kiszka via Xenomai wrote:
> From: Jan Kiszka <[email protected]>
> 
> __secure_computing, called by syscall_trace_enter, returns -1 when a
> call should be skipped. We must avoid that this is interpreted as
> EXIT_SYSCALL_OOB in the dovetail case.
> 
> Fixes, e.g., crashes of Chrome in sandbox mode.
> 
> Reported-by: Ando Yuta <[email protected]>
> Signed-off-by: Jan Kiszka <[email protected]>
> ---
> 
> "Fixes" is my observation - Yuta-san, please confirm also for your setup.
> 
>  include/linux/entry-common.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index 2a08b00632b9..43cf846111d9 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -66,8 +66,8 @@
>   * Status codes of syscall entry when Dovetail is enabled. Must not
>   * conflict with valid syscall numbers.

Maybe extend this comment why -1 can not be used here?

>   */
> -#define EXIT_SYSCALL_OOB     (-1)
> -#define EXIT_SYSCALL_TAIL    (-2)
> +#define EXIT_SYSCALL_OOB     (-2)
> +#define EXIT_SYSCALL_TAIL    (-3)
>  
>  /**
>   * arch_check_user_regs - Architecture specific sanity check for user mode 
> regs

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