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/wp.c | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 214 insertions(+) create mode 100644 tools/perf/tests/wp.c (limited to 'tools/perf/tests/wp.c') diff --git a/tools/perf/tests/wp.c b/tools/perf/tests/wp.c new file mode 100644 index 000000000..69b31f00e --- /dev/null +++ b/tools/perf/tests/wp.c @@ -0,0 +1,214 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include "tests.h" +#include "debug.h" +#include "event.h" +#include "cloexec.h" +#include "../perf-sys.h" + +#define WP_TEST_ASSERT_VAL(fd, text, val) \ +do { \ + long long count; \ + wp_read(fd, &count, sizeof(long long)); \ + TEST_ASSERT_VAL(text, count == val); \ +} while (0) + +#ifdef __i386__ +/* Only breakpoint length less-than 8 has hardware support on i386. */ +static volatile u32 data1; +#else +static volatile u64 data1; +#endif +static volatile u8 data2[3]; + +#ifndef __s390x__ +static int wp_read(int fd, long long *count, int size) +{ + int ret = read(fd, count, size); + + if (ret != size) { + pr_debug("failed to read: %d\n", ret); + return -1; + } + return 0; +} + +static void get__perf_event_attr(struct perf_event_attr *attr, int wp_type, + void *wp_addr, unsigned long wp_len) +{ + memset(attr, 0, sizeof(struct perf_event_attr)); + attr->type = PERF_TYPE_BREAKPOINT; + attr->size = sizeof(struct perf_event_attr); + attr->config = 0; + attr->bp_type = wp_type; + attr->bp_addr = (unsigned long)wp_addr; + attr->bp_len = wp_len; + attr->sample_period = 1; + attr->sample_type = PERF_SAMPLE_IP; + attr->exclude_kernel = 1; + attr->exclude_hv = 1; +} + +static int __event(int wp_type, void *wp_addr, unsigned long wp_len) +{ + int fd; + struct perf_event_attr attr; + + get__perf_event_attr(&attr, wp_type, wp_addr, wp_len); + fd = sys_perf_event_open(&attr, 0, -1, -1, + perf_event_open_cloexec_flag()); + if (fd < 0) { + fd = -errno; + pr_debug("failed opening event %x\n", attr.bp_type); + } + + return fd; +} +#endif + +static int test__wp_ro(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#if defined(__s390x__) || defined(__x86_64__) || defined(__i386__) + return TEST_SKIP; +#else + int fd; + unsigned long tmp, tmp1 = rand(); + + fd = __event(HW_BREAKPOINT_R, (void *)&data1, sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + tmp = data1; + WP_TEST_ASSERT_VAL(fd, "RO watchpoint", 1); + + data1 = tmp1 + tmp; + WP_TEST_ASSERT_VAL(fd, "RO watchpoint", 1); + + close(fd); + return 0; +#endif +} + +static int test__wp_wo(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#if defined(__s390x__) + return TEST_SKIP; +#else + int fd; + unsigned long tmp, tmp1 = rand(); + + fd = __event(HW_BREAKPOINT_W, (void *)&data1, sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + tmp = data1; + WP_TEST_ASSERT_VAL(fd, "WO watchpoint", 0); + + data1 = tmp1 + tmp; + WP_TEST_ASSERT_VAL(fd, "WO watchpoint", 1); + + close(fd); + return 0; +#endif +} + +static int test__wp_rw(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#if defined(__s390x__) + return TEST_SKIP; +#else + int fd; + unsigned long tmp, tmp1 = rand(); + + fd = __event(HW_BREAKPOINT_R | HW_BREAKPOINT_W, (void *)&data1, + sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + tmp = data1; + WP_TEST_ASSERT_VAL(fd, "RW watchpoint", 1); + + data1 = tmp1 + tmp; + WP_TEST_ASSERT_VAL(fd, "RW watchpoint", 2); + + close(fd); + return 0; +#endif +} + +static int test__wp_modify(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ +#if defined(__s390x__) + return TEST_SKIP; +#else + int fd, ret; + unsigned long tmp = rand(); + struct perf_event_attr new_attr; + + fd = __event(HW_BREAKPOINT_W, (void *)&data1, sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + data1 = tmp; + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 1); + + /* Modify watchpoint with disabled = 1 */ + get__perf_event_attr(&new_attr, HW_BREAKPOINT_W, (void *)&data2[0], + sizeof(u8) * 2); + new_attr.disabled = 1; + ret = ioctl(fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &new_attr); + if (ret < 0) { + if (errno == ENOTTY) { + test->test_cases[subtest].skip_reason = "missing kernel support"; + ret = TEST_SKIP; + } + + pr_debug("ioctl(PERF_EVENT_IOC_MODIFY_ATTRIBUTES) failed\n"); + close(fd); + return ret; + } + + data2[1] = tmp; /* Not Counted */ + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 1); + + /* Enable the event */ + ioctl(fd, PERF_EVENT_IOC_ENABLE, 0); + if (ret < 0) { + pr_debug("Failed to enable event\n"); + close(fd); + return ret; + } + + data2[1] = tmp; /* Counted */ + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 2); + + data2[2] = tmp; /* Not Counted */ + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 2); + + close(fd); + return 0; +#endif +} + +static struct test_case wp_tests[] = { + TEST_CASE_REASON("Read Only Watchpoint", wp_ro, "missing hardware support"), + TEST_CASE_REASON("Write Only Watchpoint", wp_wo, "missing hardware support"), + TEST_CASE_REASON("Read / Write Watchpoint", wp_rw, "missing hardware support"), + TEST_CASE_REASON("Modify Watchpoint", wp_modify, "missing hardware support"), + { .name = NULL, } +}; + +struct test_suite suite__wp = { + .desc = "Watchpoint", + .test_cases = wp_tests, +}; -- cgit v1.3.1