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/bcm63xx/dev-rng.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 arch/mips/bcm63xx/dev-rng.c (limited to 'arch/mips/bcm63xx/dev-rng.c') diff --git a/arch/mips/bcm63xx/dev-rng.c b/arch/mips/bcm63xx/dev-rng.c new file mode 100644 index 000000000..f94151f7c --- /dev/null +++ b/arch/mips/bcm63xx/dev-rng.c @@ -0,0 +1,40 @@ +/* + * 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) 2011 Florian Fainelli + */ + +#include +#include +#include +#include + +static struct resource rng_resources[] = { + { + .start = -1, /* filled at runtime */ + .end = -1, /* filled at runtime */ + .flags = IORESOURCE_MEM, + }, +}; + +static struct platform_device bcm63xx_rng_device = { + .name = "bcm63xx-rng", + .id = -1, + .num_resources = ARRAY_SIZE(rng_resources), + .resource = rng_resources, +}; + +static int __init bcm63xx_rng_register(void) +{ + if (!BCMCPU_IS_6368()) + return -ENODEV; + + rng_resources[0].start = bcm63xx_regset_address(RSET_RNG); + rng_resources[0].end = rng_resources[0].start; + rng_resources[0].end += RSET_RNG_SIZE - 1; + + return platform_device_register(&bcm63xx_rng_device); +} +arch_initcall(bcm63xx_rng_register); -- cgit v1.3.1