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 --- tools/perf/tests/genelf.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 tools/perf/tests/genelf.c (limited to 'tools/perf/tests/genelf.c') diff --git a/tools/perf/tests/genelf.c b/tools/perf/tests/genelf.c new file mode 100644 index 000000000..95f3be1b6 --- /dev/null +++ b/tools/perf/tests/genelf.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include + +#include "debug.h" +#include "tests.h" + +#ifdef HAVE_JITDUMP +#include +#include "../util/genelf.h" +#endif + +#define TEMPL "/tmp/perf-test-XXXXXX" + +static int test__jit_write_elf(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#ifdef HAVE_JITDUMP + static unsigned char x86_code[] = { + 0xBB, 0x2A, 0x00, 0x00, 0x00, /* movl $42, %ebx */ + 0xB8, 0x01, 0x00, 0x00, 0x00, /* movl $1, %eax */ + 0xCD, 0x80 /* int $0x80 */ + }; + char path[PATH_MAX]; + int fd, ret; + + strcpy(path, TEMPL); + + fd = mkstemp(path); + if (fd < 0) { + perror("mkstemp failed"); + return TEST_FAIL; + } + + pr_info("Writing jit code to: %s\n", path); + + ret = jit_write_elf(fd, 0, "main", x86_code, sizeof(x86_code), + NULL, 0, NULL, 0, 0); + close(fd); + + unlink(path); + + return ret ? TEST_FAIL : 0; +#else + return TEST_SKIP; +#endif +} + +DEFINE_SUITE("Test jit_write_elf", jit_write_elf); -- cgit v1.3.1