From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- net/wireless/tests/chan.c | 408 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 408 insertions(+) create mode 100644 net/wireless/tests/chan.c (limited to 'net/wireless/tests/chan.c') diff --git a/net/wireless/tests/chan.c b/net/wireless/tests/chan.c new file mode 100644 index 000000000..65eb18c49 --- /dev/null +++ b/net/wireless/tests/chan.c @@ -0,0 +1,408 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * KUnit tests for channel helper functions + * + * Copyright (C) 2023-2024, 2026 Intel Corporation + */ +#include +#include + +MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING"); + +static struct ieee80211_channel chan_2ghz_1 = { + .band = NL80211_BAND_2GHZ, + .center_freq = 2412, +}; + +static struct ieee80211_channel chan_6ghz_1 = { + .band = NL80211_BAND_6GHZ, + .center_freq = 5955, +}; + +static struct ieee80211_channel chan_6ghz_5 = { + .band = NL80211_BAND_6GHZ, + .center_freq = 5975, +}; + +static struct ieee80211_channel chan_6ghz_105 = { + .band = NL80211_BAND_6GHZ, + .center_freq = 6475, +}; + +static const struct chandef_compat_case { + const char *desc; + /* leave c1 empty for tests for identical */ + struct cfg80211_chan_def c1, c2; + /* we test both ways around, so c2 should always be the compat one */ + bool compat; +} chandef_compat_cases[] = { + { + .desc = "identical non-HT", + .c2 = { + .width = NL80211_CHAN_WIDTH_20_NOHT, + .chan = &chan_6ghz_1, + .center_freq1 = 5955, + }, + .compat = true, + }, + { + .desc = "identical 20 MHz", + .c2 = { + .width = NL80211_CHAN_WIDTH_20, + .chan = &chan_6ghz_1, + .center_freq1 = 5955, + }, + .compat = true, + }, + { + .desc = "identical 40 MHz", + .c2 = { + .width = NL80211_CHAN_WIDTH_40, + .chan = &chan_6ghz_1, + .center_freq1 = 5955 + 10, + }, + .compat = true, + }, + { + .desc = "identical 80 MHz", + .c2 = { + .width = NL80211_CHAN_WIDTH_80, + .chan = &chan_6ghz_1, + .center_freq1 = 5955 + 10 + 20, + }, + .compat = true, + }, + { + .desc = "identical 160 MHz", + .c2 = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_1, + .center_freq1 = 5955 + 10 + 20 + 40, + }, + .compat = true, + }, + { + .desc = "identical 320 MHz", + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_1, + .center_freq1 = 5955 + 10 + 20 + 40 + 80, + }, + .compat = true, + }, + { + .desc = "20 MHz in 320 MHz\n", + .c1 = { + .width = NL80211_CHAN_WIDTH_20, + .chan = &chan_6ghz_1, + .center_freq1 = 5955, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_1, + .center_freq1 = 5955 + 10 + 20 + 40 + 80, + }, + .compat = true, + }, + { + .desc = "different 20 MHz", + .c1 = { + .width = NL80211_CHAN_WIDTH_20, + .chan = &chan_6ghz_1, + .center_freq1 = 5955, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_20, + .chan = &chan_6ghz_5, + .center_freq1 = 5975, + }, + }, + { + .desc = "different primary 320 MHz", + .c1 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 110, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 - 50, + }, + }, + { + /* similar to previous test but one has lower BW */ + .desc = "matching primary 160 MHz", + .c1 = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 - 50, + }, + .compat = true, + }, + { + .desc = "matching primary 160 MHz & punctured secondary 160 Mhz", + .c1 = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 - 50, + .punctured = 0xf, + }, + .compat = true, + }, + { + .desc = "matching primary 160 MHz & punctured matching", + .c1 = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0xc0, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 - 50, + .punctured = 0xc000, + }, + .compat = true, + }, + { + .desc = "matching primary 160 MHz & punctured not matching", + .c1 = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x80, + }, + .c2 = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 - 50, + .punctured = 0xc000, + }, + }, +}; + +KUNIT_ARRAY_PARAM_DESC(chandef_compat, chandef_compat_cases, desc) + +static void test_chandef_compat(struct kunit *test) +{ + const struct chandef_compat_case *params = test->param_value; + const struct cfg80211_chan_def *ret, *expect; + struct cfg80211_chan_def c1 = params->c1; + + /* tests with identical ones */ + if (!params->c1.chan) + c1 = params->c2; + + KUNIT_EXPECT_EQ(test, cfg80211_chandef_valid(&c1), true); + KUNIT_EXPECT_EQ(test, cfg80211_chandef_valid(¶ms->c2), true); + + expect = params->compat ? ¶ms->c2 : NULL; + + ret = cfg80211_chandef_compatible(&c1, ¶ms->c2); + KUNIT_EXPECT_PTR_EQ(test, ret, expect); + + if (!params->c1.chan) + expect = &c1; + + ret = cfg80211_chandef_compatible(¶ms->c2, &c1); + KUNIT_EXPECT_PTR_EQ(test, ret, expect); +} + +static const struct chandef_dbe_case { + const char *desc; + struct cfg80211_chan_def c; + u8 dbe[3]; + bool fails; + u16 cf1; +} chandef_dbe_cases[] = { + { + .desc = "non-HT failure", + .c = { + .width = NL80211_CHAN_WIDTH_20_NOHT, + .chan = &chan_6ghz_1, + .center_freq1 = 5955, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_40, + .fails = true, + }, + { + .desc = "2.4 GHz fails", + .c = { + .width = NL80211_CHAN_WIDTH_20, + .chan = &chan_2ghz_1, + .center_freq1 = 2412, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_40, + .fails = true, + }, + { + .desc = "DBE narrower", + .c = { + .width = NL80211_CHAN_WIDTH_320, + .chan = &chan_6ghz_1, + .center_freq1 = 5955 + 10 + 20 + 40 + 80, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_160, + .fails = true, + }, + { + .desc = "DBE to 320-1", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_1, + .cf1 = 6425, + }, + { + .desc = "DBE to 320-2", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_2, + .cf1 = 6585, + }, + { + .desc = "bad disabled subchannel bitmap - not enough in BSS (1)", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0001, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_1 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0 */ + .fails = true, + }, + { + .desc = "bad disabled subchannel bitmap - too much in BSS (1)", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0001, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_1 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0x0300 */ + .dbe[2] = 0x03, + .fails = true, + }, + { + .desc = "bad disabled subchannel bitmap - not enough in BSS (2)", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0001, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_2 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0 */ + .fails = true, + }, + { + .desc = "bad disabled subchannel bitmap - too much in BSS (2)", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0001, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_2 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0x03 */ + .dbe[1] = 0x03, + .fails = true, + }, + { + .desc = "bad disabled subchannel bitmap - bad bitmap", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0001, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_1 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0x1100 */ + .dbe[2] = 0x11, + .fails = true, + }, + { + .desc = "good disabled subchannel bitmap (1)", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0003, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_1 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0x0300 */ + .dbe[2] = 0x03, + .cf1 = 6425, + }, + { + .desc = "good disabled subchannel bitmap (2)", + .c = { + .width = NL80211_CHAN_WIDTH_160, + .chan = &chan_6ghz_105, + .center_freq1 = 6475 + 30, + .punctured = 0x0003, + }, + .dbe[0] = IEEE80211_UHR_DBE_OPER_BW_320_2 | + IEEE80211_UHR_DBE_OPER_DIS_SUBCHANNEL_BITMAP_PRES, + /* DBE disabled subchannel bitmap == 0x0003 */ + .dbe[1] = 0x03, + .cf1 = 6585, + }, +}; + +KUNIT_ARRAY_PARAM_DESC(chandef_dbe, chandef_dbe_cases, desc) + +static void test_chandef_dbe(struct kunit *test) +{ + const struct chandef_dbe_case *params = test->param_value; + struct cfg80211_chan_def c = params->c; + int ret; + + KUNIT_EXPECT_EQ(test, cfg80211_chandef_valid(¶ms->c), true); + + ret = cfg80211_chandef_add_dbe(&c, (void *)params->dbe); + KUNIT_EXPECT_EQ(test, ret != 0, params->fails); + + if (params->fails) + return; + + KUNIT_EXPECT_EQ(test, c.center_freq1, params->cf1); +} + +static struct kunit_case chandef_test_cases[] = { + KUNIT_CASE_PARAM(test_chandef_compat, chandef_compat_gen_params), + KUNIT_CASE_PARAM(test_chandef_dbe, chandef_dbe_gen_params), + {} +}; + +static struct kunit_suite chandef = { + .name = "cfg80211-chandef", + .test_cases = chandef_test_cases, +}; + +kunit_test_suite(chandef); -- cgit v1.3.1