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, 48 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-s3c.h b/drivers/rtc/rtc-s3c.h
new file mode 100644
index 000000000..11d7a1255
--- /dev/null
+++ b/drivers/rtc/rtc-s3c.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2003 Simtec Electronics <linux@simtec.co.uk>
+ *		      http://www.simtec.co.uk/products/SWLINUX/
+ *
+ * S3C2410 Internal RTC register definition
+*/
+
+#ifndef __ASM_ARCH_REGS_RTC_H
+#define __ASM_ARCH_REGS_RTC_H __FILE__
+
+#define S3C2410_RTCREG(x) (x)
+#define S3C2410_INTP		S3C2410_RTCREG(0x30)
+#define S3C2410_INTP_ALM	(1 << 1)
+#define S3C2410_INTP_TIC	(1 << 0)
+
+#define S3C2410_RTCCON		S3C2410_RTCREG(0x40)
+#define S3C2410_RTCCON_RTCEN	(1 << 0)
+#define S3C2410_RTCCON_CNTSEL	(1 << 2)
+#define S3C2410_RTCCON_CLKRST	(1 << 3)
+#define S3C2443_RTCCON_TICSEL	(1 << 4)
+#define S3C64XX_RTCCON_TICEN	(1 << 8)
+
+#define S3C2410_RTCALM		S3C2410_RTCREG(0x50)
+#define S3C2410_RTCALM_ALMEN	(1 << 6)
+#define S3C2410_RTCALM_YEAREN	(1 << 5)
+#define S3C2410_RTCALM_MONEN	(1 << 4)
+#define S3C2410_RTCALM_DAYEN	(1 << 3)
+#define S3C2410_RTCALM_HOUREN	(1 << 2)
+#define S3C2410_RTCALM_MINEN	(1 << 1)
+#define S3C2410_RTCALM_SECEN	(1 << 0)
+
+#define S3C2410_ALMSEC		S3C2410_RTCREG(0x54)
+#define S3C2410_ALMMIN		S3C2410_RTCREG(0x58)
+#define S3C2410_ALMHOUR		S3C2410_RTCREG(0x5c)
+
+#define S3C2410_ALMDATE		S3C2410_RTCREG(0x60)
+#define S3C2410_ALMMON		S3C2410_RTCREG(0x64)
+#define S3C2410_ALMYEAR		S3C2410_RTCREG(0x68)
+
+#define S3C2410_RTCSEC		S3C2410_RTCREG(0x70)
+#define S3C2410_RTCMIN		S3C2410_RTCREG(0x74)
+#define S3C2410_RTCHOUR		S3C2410_RTCREG(0x78)
+#define S3C2410_RTCDATE		S3C2410_RTCREG(0x7c)
+#define S3C2410_RTCMON		S3C2410_RTCREG(0x84)
+#define S3C2410_RTCYEAR		S3C2410_RTCREG(0x88)
+
+#endif /* __ASM_ARCH_REGS_RTC_H */