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/bitops.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 162 insertions(+) create mode 100644 arch/mips/lib/bitops.c (limited to 'arch/mips/lib/bitops.c') diff --git a/arch/mips/lib/bitops.c b/arch/mips/lib/bitops.c new file mode 100644 index 000000000..00aee98e9 --- /dev/null +++ b/arch/mips/lib/bitops.c @@ -0,0 +1,162 @@ +/* + * 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) 1994-1997, 99, 2000, 06, 07 Ralf Baechle (ralf@linux-mips.org) + * Copyright (c) 1999, 2000 Silicon Graphics, Inc. + */ +#include +#include +#include +#include + + +/** + * __mips_set_bit - Atomically set a bit in memory. This is called by + * set_bit() if it cannot find a faster solution. + * @nr: the bit to set + * @addr: the address to start counting from + */ +void __mips_set_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a |= mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_set_bit); + + +/** + * __mips_clear_bit - Clears a bit in memory. This is called by clear_bit() if + * it cannot find a faster solution. + * @nr: Bit to clear + * @addr: Address to start counting from + */ +void __mips_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a &= ~mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_clear_bit); + + +/** + * __mips_change_bit - Toggle a bit in memory. This is called by change_bit() + * if it cannot find a faster solution. + * @nr: Bit to change + * @addr: Address to start counting from + */ +void __mips_change_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a ^= mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_change_bit); + + +/** + * __mips_test_and_set_bit_lock - Set a bit and return its old value. This is + * called by test_and_set_bit_lock() if it cannot find a faster solution. + * @nr: Bit to set + * @addr: Address to count from + */ +int __mips_test_and_set_bit_lock(unsigned long nr, + volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a |= mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_set_bit_lock); + + +/** + * __mips_test_and_clear_bit - Clear a bit and return its old value. This is + * called by test_and_clear_bit() if it cannot find a faster solution. + * @nr: Bit to clear + * @addr: Address to count from + */ +int __mips_test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a &= ~mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_clear_bit); + + +/** + * __mips_test_and_change_bit - Change a bit and return its old value. This is + * called by test_and_change_bit() if it cannot find a faster solution. + * @nr: Bit to change + * @addr: Address to count from + */ +int __mips_test_and_change_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a ^= mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_change_bit); + +bool __mips_xor_is_negative_byte(unsigned long mask, + volatile unsigned long *addr) +{ + unsigned long flags; + unsigned long data; + + raw_local_irq_save(flags); + data = *addr; + *addr = data ^ mask; + raw_local_irq_restore(flags); + + return (data & BIT(7)) != 0; +} -- cgit v1.3.1