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 8659a0e0efdd975c73355dbc033f79ba3b31e82c Mon Sep 17 00:00:00 2001
From: Michael Ellerman mpe@ellerman.id.au Date: Wed, 20 May 2020 23:36:05 +1000 Subject: [PATCH] powerpc/64s: Disable STRICT_KERNEL_RWX
Several strange crashes have been eventually traced back to STRICT_KERNEL_RWX and its interaction with code patching.
Various paths in our ftrace, kprobes and other patching code need to be hardened against patching failures, otherwise we can end up running with partially/incorrectly patched ftrace paths, kprobes or jump labels, which can then cause strange crashes.
Although fixes for those are in development, they're not -rc material.
There also seem to be problems with the underlying strict RWX logic, which needs further debugging.
So for now disable STRICT_KERNEL_RWX on 64-bit to prevent people from enabling the option and tripping over the bugs.
Fixes: 1e0fc9d1eb2b ("powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs") Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20200520133605.972649-1-mpe@ellerman.id.au
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 924c541a9260..d13b5328ca10 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -130,7 +130,7 @@ config PPC select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_MEMBARRIER_CALLBACKS select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64 - select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION) + select ARCH_HAS_STRICT_KERNEL_RWX if (PPC32 && !HIBERNATION) select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAS_UACCESS_FLUSHCACHE select ARCH_HAS_UACCESS_MCSAFE if PPC64