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, 36 insertions, 0 deletions

diff --git a/drivers/dma/dw/Kconfig b/drivers/dma/dw/Kconfig
new file mode 100644
index 000000000..a9828ddd6
--- /dev/null
+++ b/drivers/dma/dw/Kconfig
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0
+
+#
+# DMA engine configuration for dw
+#
+
+config DW_DMAC_CORE
+	tristate
+	select DMA_ENGINE
+
+config DW_DMAC
+	tristate "Synopsys DesignWare AHB DMA platform driver"
+	depends on HAS_IOMEM
+	select DW_DMAC_CORE
+	help
+	  Support the Synopsys DesignWare AHB DMA controller. This
+	  can be integrated in chips such as the Intel Cherrytrail.
+
+config RZN1_DMAMUX
+	tristate "Renesas RZ/N1 DMAMUX driver"
+	depends on DW_DMAC
+	depends on ARCH_RZN1 || COMPILE_TEST
+	help
+	  Support the Renesas RZ/N1 DMAMUX which is located in front of
+	  the Synopsys DesignWare AHB DMA controller located on Renesas
+	  SoCs.
+
+config DW_DMAC_PCI
+	tristate "Synopsys DesignWare AHB DMA PCI driver"
+	depends on PCI
+	depends on HAS_IOMEM
+	select DW_DMAC_CORE
+	help
+	  Support the Synopsys DesignWare AHB DMA controller on the
+	  platforms that enumerate it as a PCI device. For example,
+	  Intel Medfield has integrated this GPDMA controller.