From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- arch/mips/Makefile.postlink | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 arch/mips/Makefile.postlink (limited to 'arch/mips/Makefile.postlink') diff --git a/arch/mips/Makefile.postlink b/arch/mips/Makefile.postlink new file mode 100644 index 000000000..ea0add7d5 --- /dev/null +++ b/arch/mips/Makefile.postlink @@ -0,0 +1,41 @@ +# SPDX-License-Identifier: GPL-2.0 +# =========================================================================== +# Post-link MIPS pass +# =========================================================================== +# +# 1. Check that Loongson3 LL/SC workarounds are applied correctly +# 2. Insert relocations into vmlinux + +PHONY := __archpost +__archpost: + +-include include/config/auto.conf +include $(srctree)/scripts/Kbuild.include + +CMD_LS3_LLSC = arch/mips/tools/loongson3-llsc-check +quiet_cmd_ls3_llsc = LLSCCHK $@ + cmd_ls3_llsc = $(CMD_LS3_LLSC) $@ + +CMD_RELOCS = arch/mips/boot/tools/relocs +quiet_cmd_relocs = RELOCS $@ + cmd_relocs = $(CMD_RELOCS) $@ + +# `@true` prevents complaint when there is nothing to be done + +vmlinux vmlinux.unstripped: FORCE + @true +ifeq ($(CONFIG_CPU_LOONGSON3_WORKAROUNDS),y) + $(call if_changed,ls3_llsc) +endif +ifeq ($(CONFIG_RELOCATABLE),y) + $(call if_changed,relocs) +endif + +clean: + @true + +PHONY += FORCE clean + +FORCE: + +.PHONY: $(PHONY) -- cgit v1.3.1