openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

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 <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
new file mode 100644
index 000000000..304692391
--- /dev/null
+++ b/arch/mips/mm/Makefile
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux/MIPS-specific parts of the memory manager.
+#
+
+obj-y				+= cache.o
+obj-y				+= context.o
+obj-y				+= extable.o
+obj-y				+= fault.o
+obj-y				+= init.o
+obj-y				+= mmap.o
+obj-y				+= page.o
+obj-y				+= page-funcs.o
+obj-y				+= pgtable.o
+obj-y				+= tlbex.o
+obj-y				+= tlbex-fault.o
+obj-y				+= tlb-funcs.o
+
+ifdef CONFIG_CPU_MICROMIPS
+obj-y				+= uasm-micromips.o
+else
+obj-y				+= uasm-mips.o
+endif
+
+ifndef CONFIG_EVA
+obj-y				+= maccess.o
+endif
+
+obj-$(CONFIG_32BIT)		+= ioremap.o pgtable-32.o
+obj-$(CONFIG_64BIT)		+= ioremap64.o pgtable-64.o
+obj-$(CONFIG_HIGHMEM)		+= highmem.o
+obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
+obj-$(CONFIG_DMA_NONCOHERENT)	+= dma-noncoherent.o
+
+obj-$(CONFIG_CPU_R3K_TLB)	+= tlb-r3k.o
+obj-$(CONFIG_CPU_R4K_CACHE_TLB) += c-r4k.o cex-gen.o tlb-r4k.o
+obj-$(CONFIG_CPU_R3000)		+= c-r3k.o
+obj-$(CONFIG_CPU_SB1)		+= c-r4k.o cerr-sb1.o cex-sb1.o tlb-r4k.o
+obj-$(CONFIG_CPU_CAVIUM_OCTEON) += c-octeon.o cex-oct.o tlb-r4k.o
+
+obj-$(CONFIG_IP22_CPU_SCACHE)	+= sc-ip22.o
+obj-$(CONFIG_R5000_CPU_SCACHE)	+= sc-r5k.o
+obj-$(CONFIG_RM7000_CPU_SCACHE) += sc-rm7k.o
+obj-$(CONFIG_MIPS_CPU_SCACHE)	+= sc-mips.o
+obj-$(CONFIG_SCACHE_DEBUGFS)	+= sc-debugfs.o
+
+obj-$(CONFIG_DEBUG_VIRTUAL)	+= physaddr.o