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/lib/delay.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 arch/mips/lib/delay.c (limited to 'arch/mips/lib/delay.c') diff --git a/arch/mips/lib/delay.c b/arch/mips/lib/delay.c new file mode 100644 index 000000000..ccdb1fc1e --- /dev/null +++ b/arch/mips/lib/delay.c @@ -0,0 +1,68 @@ +/* + * 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) 1994 by Waldorf Electronics + * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle + * Copyright (C) 1999, 2000 Silicon Graphics, Inc. + * Copyright (C) 2007, 2014 Maciej W. Rozycki + */ +#include +#include +#include +#include +#include + +#include +#include + +#ifndef CONFIG_CPU_DADDI_WORKAROUNDS +#define GCC_DADDI_IMM_ASM() "I" +#else +#define GCC_DADDI_IMM_ASM() "r" +#endif + +#ifndef CONFIG_HAVE_PLAT_DELAY + +void __delay(unsigned long loops) +{ + __asm__ __volatile__ ( + " .set noreorder \n" + " .align 3 \n" + "1: bnez %0, 1b \n" + " " __stringify(LONG_SUBU) " %0, %1 \n" + " .set reorder \n" + : "=r" (loops) + : GCC_DADDI_IMM_ASM() (1), "0" (loops)); +} +EXPORT_SYMBOL(__delay); + +/* + * Division by multiplication: you don't have to worry about + * loss of precision. + * + * Use only for very small delays ( < 1 msec). Should probably use a + * lookup table, really, as the multiplications take much too long with + * short delays. This is a "reasonable" implementation, though (and the + * first constant multiplications gets optimized away if the delay is + * a constant) + */ + +void __udelay(unsigned long us) +{ + unsigned int lpj = raw_current_cpu_data.udelay_val; + + __delay((us * 0x000010c7ull * HZ * lpj) >> 32); +} +EXPORT_SYMBOL(__udelay); + +void __ndelay(unsigned long ns) +{ + unsigned int lpj = raw_current_cpu_data.udelay_val; + + __delay((ns * 0x00000005ull * HZ * lpj) >> 32); +} +EXPORT_SYMBOL(__ndelay); + +#endif -- cgit v1.3.1