signal/s390: Use force_sigsegv in default_trap_handler
authorEric W. Biederman <ebiederm@xmission.com>
Wed, 20 Oct 2021 17:43:57 +0000 (12:43 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 25 Nov 2021 08:49:06 +0000 (09:49 +0100)
commit58484ab427f147cf0d2c1ff912294ee9e001ed2e
tree8dec30a8ff018ddb589f6f35e2529d7afca0090b
parentc7b7868dba816bfda54d5036ae5bb9365dac5c8a
signal/s390: Use force_sigsegv in default_trap_handler

commit 9bc508cf0791c8e5a37696de1a046d746fcbd9d8 upstream.

Reading the history it is unclear why default_trap_handler calls
do_exit.  It is not even menthioned in the commit where the change
happened.  My best guess is that because it is unknown why the
exception happened it was desired to guarantee the process never
returned to userspace.

Using do_exit(SIGSEGV) has the problem that it will only terminate one
thread of a process, leaving the process in an undefined state.

Use force_sigsegv(SIGSEGV) instead which effectively has the same
behavior except that is uses the ordinary signal mechanism and
terminates all threads of a process and is generally well defined.

Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Fixes: ca2ab03237ec ("[PATCH] s390: core changes")
History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: https://lkml.kernel.org/r/20211020174406.17889-11-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Thomas Backlund <tmb@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/s390/kernel/traps.c