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/dec/wbflush.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 arch/mips/dec/wbflush.c (limited to 'arch/mips/dec/wbflush.c') diff --git a/arch/mips/dec/wbflush.c b/arch/mips/dec/wbflush.c new file mode 100644 index 000000000..dad64d178 --- /dev/null +++ b/arch/mips/dec/wbflush.c @@ -0,0 +1,92 @@ +/* + * Setup the right wbflush routine for the different DECstations. + * + * Created with information from: + * DECstation 3100 Desktop Workstation Functional Specification + * DECstation 5000/200 KN02 System Module Functional Specification + * mipsel-linux-objdump --disassemble vmunix | grep "wbflush" :-) + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 1998 Harald Koerfgen + * Copyright (C) 2002 Maciej W. Rozycki + */ + +#include +#include + +#include +#include +#include + +static void wbflush_kn01(void); +static void wbflush_kn210(void); +static void wbflush_mips(void); + +void (*__wbflush) (void); + +void __init wbflush_setup(void) +{ + switch (mips_machtype) { + case MACH_DS23100: + case MACH_DS5000_200: /* DS5000 3max */ + __wbflush = wbflush_kn01; + break; + case MACH_DS5100: /* DS5100 MIPSMATE */ + __wbflush = wbflush_kn210; + break; + case MACH_DS5000_1XX: /* DS5000/100 3min */ + case MACH_DS5000_XX: /* Personal DS5000/2x */ + case MACH_DS5000_2X0: /* DS5000/240 3max+ */ + case MACH_DS5900: /* DS5900 bigmax */ + default: + __wbflush = wbflush_mips; + break; + } +} + +/* + * For the DS3100 and DS5000/200 the R2020/R3220 writeback buffer functions + * as part of Coprocessor 0. + */ +static void wbflush_kn01(void) +{ + asm(".set\tpush\n\t" + ".set\tnoreorder\n\t" + "1:\tbc0f\t1b\n\t" + "nop\n\t" + ".set\tpop"); +} + +/* + * For the DS5100 the writeback buffer seems to be a part of Coprocessor 3. + * But CP3 has to enabled first. + */ +static void wbflush_kn210(void) +{ + asm(".set\tpush\n\t" + ".set\tnoreorder\n\t" + "mfc0\t$2,$12\n\t" + "lui\t$3,0x8000\n\t" + "or\t$3,$2,$3\n\t" + "mtc0\t$3,$12\n\t" + "nop\n" + "1:\tbc3f\t1b\n\t" + "nop\n\t" + "mtc0\t$2,$12\n\t" + "nop\n\t" + ".set\tpop" + : : : "$2", "$3"); +} + +/* + * I/O ASIC systems use a standard writeback buffer that gets flushed + * upon an uncached read. + */ +static void wbflush_mips(void) +{ + __fast_iob(); +} +EXPORT_SYMBOL(__wbflush); -- cgit v1.3.1