ACK: [PATCH 0/2] Fix invalid syscall return for traced tasks

[Colin Ian King]

On 21/04/2021 19:40, Dan Streetman wrote:
> BugLink: https://bugs.launchpad.net/bugs/1895132
> 
> For any traced task, that has _TIF_TRACED set, invalid syscalls are
> sent to the tracing code, which returns EPERM instead of ENOSYS, and
> breaks userspace.
> 
> Note that in focal (5.4) the return value was the actual syscall number,
> while in bionic the return value is EPERM. However either value breaks
> userspace.
> 
> This is causing narrow failures of hirsute containers on bionic hosts
> that are running the 4.15 kernel, as detailed in bug 1916485.
> 
> Sven Schnelle (2):
>   s390/ptrace: return -ENOSYS when invalid syscall is supplied
>   s390/ptrace: pass invalid syscall numbers to tracing
> 
>  arch/s390/kernel/entry.S  |  2 +-
>  arch/s390/kernel/ptrace.c | 23 ++++++++++++++---------
>  2 files changed, 15 insertions(+), 10 deletions(-)
> 

Looks good to me, backport looks OK for patch 2.

Acked-by: Colin Ian King <colin.king at canonical.com>