The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 82e10af2248d2d09c99834613f1b47d5002dc379 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" ebiederm@xmission.com Date: Thu, 16 May 2019 10:55:21 -0500 Subject: [PATCH] signal/arm64: Use force_sig not force_sig_fault for SIGKILL
I don't think this is userspace visible but SIGKILL does not have any si_codes that use the fault member of the siginfo union. Correct this the simple way and call force_sig instead of force_sig_fault when the signal is SIGKILL.
The two know places where synchronous SIGKILL are generated are do_bad_area and fpsimd_save. The call paths to force_sig_fault are: do_bad_area arm64_force_sig_fault force_sig_fault force_signal_inject arm64_notify_die arm64_force_sig_fault force_sig_fault
Which means correcting this in arm64_force_sig_fault is enough to ensure the arm64 code is not misusing the generic code, which could lead to maintenance problems later.
Cc: stable@vger.kernel.org Cc: Dave Martin Dave.Martin@arm.com Cc: James Morse james.morse@arm.com Cc: Will Deacon will.deacon@arm.com Acked-by: Will Deacon will.deacon@arm.com Fixes: af40ff687bc9 ("arm64: signal: Ensure si_code is valid for all fault signals") Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index ade32046f3fe..e45d5b440fb1 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -256,7 +256,10 @@ void arm64_force_sig_fault(int signo, int code, void __user *addr, const char *str) { arm64_show_signal(signo, str); - force_sig_fault(signo, code, addr, current); + if (signo == SIGKILL) + force_sig(SIGKILL, current); + else + force_sig_fault(signo, code, addr, current); }
void arm64_force_sig_mceerr(int code, void __user *addr, short lsb,