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Mon, 29 Sep 2025 19:45:04 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Randy Dunlap , Marco Elver , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. 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Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v6 09/23] mm/ksw: ignore false positives from exit trampolines Date: Tue, 30 Sep 2025 10:43:30 +0800 Message-ID: <20250930024402.1043776-10-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250930024402.1043776-1-wangjinchao600@gmail.com> References: <20250930024402.1043776-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 8A9BF40006 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: peip7bbq1ce934tn7tg7a7cw9sjwomqq X-HE-Tag: 1759200306-230399 X-HE-Meta: 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 wsd2fo8m 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Because trampolines run after the watched function returns but before the exit_handler is called, and in the original stack frame, so the trampoline code may overwrite the watched stack address. These false positives should be ignored. is_ftrace_trampoline() does not cover all trampolines, so add a local check to handle the remaining cases. Signed-off-by: Jinchao Wang --- mm/kstackwatch/watch.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c index 887cc13292dc..722ffd9fda7c 100644 --- a/mm/kstackwatch/watch.c +++ b/mm/kstackwatch/watch.c @@ -2,6 +2,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include +#include #include #include #include @@ -18,10 +19,46 @@ bool panic_on_catch; module_param(panic_on_catch, bool, 0644); MODULE_PARM_DESC(panic_on_catch, "panic immediately on corruption catch"); +#define TRAMPOLINE_NAME "return_to_handler" +#define TRAMPOLINE_DEPTH 16 + +/* Resolved once, then reused */ +static unsigned long tramp_start, tramp_end; + +static void ksw_watch_resolve_trampoline(void) +{ + unsigned long sz, off; + + if (likely(tramp_start && tramp_end)) + return; + + tramp_start = kallsyms_lookup_name(TRAMPOLINE_NAME); + if (tramp_start && kallsyms_lookup_size_offset(tramp_start, &sz, &off)) + tramp_end = tramp_start + sz; +} + +static bool ksw_watch_in_trampoline(unsigned long ip) +{ + if (tramp_start && tramp_end && ip >= tramp_start && ip < tramp_end) + return true; + return false; +} static void ksw_watch_handler(struct perf_event *bp, struct perf_sample_data *data, struct pt_regs *regs) { + unsigned long entries[TRAMPOLINE_DEPTH]; + int i, nr = 0; + + nr = stack_trace_save_regs(regs, entries, TRAMPOLINE_DEPTH, 0); + for (i = 0; i < nr; i++) { + //ignore trampoline + if (is_ftrace_trampoline(entries[i])) + return; + if (ksw_watch_in_trampoline(entries[i])) + return; + } + pr_err("========== KStackWatch: Caught stack corruption =======\n"); pr_err("config %s\n", ksw_get_config()->user_input); dump_stack(); @@ -168,6 +205,7 @@ int ksw_watch_init(void) { int ret; + ksw_watch_resolve_trampoline(); ret = ksw_watch_alloc(); if (ret <= 0) return -EBUSY; -- 2.43.0