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| author | Ali Ahmet Memis <ali@iusegentoo.com> | 2026-08-21 01:45:27 +0000 |
|---|---|---|
| committer | Stafford Horne <shorne@gmail.com> | 2026-08-29 07:32:26 +0100 |
| commit | 78004e9a87f240df03e2f73120d291763c32e0a7 (patch) | |
| tree | 137c22dd795222931b9d2bf2501d37cd766741aa /arch/powerpc/lib/quad.S | |
| download | linux-stable-78004e9a87f240df03e2f73120d291763c32e0a7.tar.gz linux-stable-78004e9a87f240df03e2f73120d291763c32e0a7.zip | |
openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted
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 <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>
Diffstat (limited to 'arch/powerpc/lib/quad.S')
| -rw-r--r-- | arch/powerpc/lib/quad.S | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/powerpc/lib/quad.S b/arch/powerpc/lib/quad.S new file mode 100644 index 000000000..da71760e5 --- /dev/null +++ b/arch/powerpc/lib/quad.S @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Quadword loads and stores + * for use in instruction emulation. + * + * Copyright 2017 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com> + */ + +#include <asm/processor.h> +#include <asm/ppc_asm.h> +#include <asm/ppc-opcode.h> +#include <asm/reg.h> +#include <asm/asm-offsets.h> +#include <linux/errno.h> + +/* do_lq(unsigned long ea, unsigned long *regs) */ +_GLOBAL(do_lq) +1: lq r6, 0(r3) + std r6, 0(r4) + std r7, 8(r4) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) + +/* do_stq(unsigned long ea, unsigned long val0, unsigned long val1) */ +_GLOBAL(do_stq) +1: stq r4, 0(r3) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) + +/* do_lqarx(unsigned long ea, unsigned long *regs) */ +_GLOBAL(do_lqarx) +1: PPC_LQARX(6, 0, 3, 0) + std r6, 0(r4) + std r7, 8(r4) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) + +/* do_stqcx(unsigned long ea, unsigned long val0, unsigned long val1, + unsigned int *crp) */ + +_GLOBAL(do_stqcx) +1: PPC_STQCX(4, 0, 3) + mfcr r5 + stw r5, 0(r6) + li r3, 0 + blr +2: li r3, -EFAULT + blr + EX_TABLE(1b, 2b) |