From 26d5badbccddcc063dc5174a2baffd13a23322aa Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 20 Oct 2021 12:43:59 -0500 Subject: signal: Implement force_fatal_sig Add a simple helper force_fatal_sig that causes a signal to be delivered to a process as if the signal handler was set to SIG_DFL. Reimplement force_sigsegv based upon this new helper. This fixes force_sigsegv so that when it forces the default signal handler to be used the code now forces the signal to be unblocked as well. Reusing the tested logic in force_sig_info_to_task that was built for force_sig_seccomp this makes the implementation trivial. This is interesting both because it makes force_sigsegv simpler and because there are a couple of buggy places in the kernel that call do_exit(SIGILL) or do_exit(SIGSYS) because there is no straight forward way today for those places to simply force the exit of a process with the chosen signal. Creating force_fatal_sig allows those places to be implemented with normal signal exits. Link: https://lkml.kernel.org/r/20211020174406.17889-13-ebiederm@xmission.com Signed-off-by: Eric W. Biederman --- kernel/signal.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index 952741f6d0f9..6a5e1802b9a2 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1662,6 +1662,19 @@ void force_sig(int sig) } EXPORT_SYMBOL(force_sig); +void force_fatal_sig(int sig) +{ + struct kernel_siginfo info; + + clear_siginfo(&info); + info.si_signo = sig; + info.si_errno = 0; + info.si_code = SI_KERNEL; + info.si_pid = 0; + info.si_uid = 0; + force_sig_info_to_task(&info, current, true); +} + /* * When things go south during signal handling, we * will force a SIGSEGV. And if the signal that caused @@ -1670,15 +1683,10 @@ EXPORT_SYMBOL(force_sig); */ void force_sigsegv(int sig) { - struct task_struct *p = current; - - if (sig == SIGSEGV) { - unsigned long flags; - spin_lock_irqsave(&p->sighand->siglock, flags); - p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; - spin_unlock_irqrestore(&p->sighand->siglock, flags); - } - force_sig(SIGSEGV); + if (sig == SIGSEGV) + force_fatal_sig(SIGSEGV); + else + force_sig(SIGSEGV); } int force_sig_fault_to_task(int sig, int code, void __user *addr -- cgit v1.2.1