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/m68k/coldfire/cache.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 arch/m68k/coldfire/cache.c (limited to 'arch/m68k/coldfire/cache.c') diff --git a/arch/m68k/coldfire/cache.c b/arch/m68k/coldfire/cache.c new file mode 100644 index 000000000..98ee89b87 --- /dev/null +++ b/arch/m68k/coldfire/cache.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +/***************************************************************************/ + +/* + * cache.c -- general ColdFire Cache maintenance code + * + * Copyright (C) 2010, Greg Ungerer (gerg@snapgear.com) + */ + +/***************************************************************************/ + +#include +#include +#include + +/***************************************************************************/ +#ifdef CACHE_PUSH +/***************************************************************************/ + +/* + * Use cpushl to push all dirty cache lines back to memory. + * Older versions of GAS don't seem to know how to generate the + * ColdFire cpushl instruction... Oh well, bit stuff it for now. + */ + +void mcf_cache_push(void) +{ + __asm__ __volatile__ ( + "clrl %%d0\n\t" + "1:\n\t" + "movel %%d0,%%a0\n\t" + "2:\n\t" + ".word 0xf468\n\t" + "addl %0,%%a0\n\t" + "cmpl %1,%%a0\n\t" + "blt 2b\n\t" + "addql #1,%%d0\n\t" + "cmpil %2,%%d0\n\t" + "bne 1b\n\t" + : /* No output */ + : "i" (CACHE_LINE_SIZE), + "i" (DCACHE_SIZE / CACHE_WAYS), + "i" (CACHE_WAYS) + : "d0", "a0" ); +} + +/***************************************************************************/ +#endif /* CACHE_PUSH */ +/***************************************************************************/ -- cgit v1.3.1