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Mon, 10 Nov 2025 08:37:21 -0800 (PST) From: Jinchao Wang To: Andrew Morton , "Masami Hiramatsu (Google)" , Peter Zijlstra , Randy Dunlap , Marco Elver , Mike Rapoport , Alexander Potapenko , Adrian Hunter , Alexander Shishkin , Alice Ryhl , Andrey Konovalov , Andrey Ryabinin , Andrii Nakryiko , Ard Biesheuvel , Arnaldo Carvalho de Melo , Ben Segall , Bill Wendling , Borislav Petkov , Catalin Marinas , Dave Hansen , David Hildenbrand , David Kaplan , "David S. Miller" , Dietmar Eggemann , Dmitry Vyukov , "H. Peter Anvin" , Ian Rogers , Ingo Molnar , James Clark , Jinchao Wang , Jinjie Ruan , Jiri Olsa , Jonathan Corbet , Juri Lelli , Justin Stitt , kasan-dev@googlegroups.com, Kees Cook , "Liam R. Howlett" , "Liang Kan" , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, llvm@lists.linux.dev, Lorenzo Stoakes , Mark Rutland , Masahiro Yamada , Mathieu Desnoyers , Mel Gorman , Michal Hocko , Miguel Ojeda , Nam Cao , Namhyung Kim , Nathan Chancellor , Naveen N Rao , Nick Desaulniers , Rong Xu , Sami Tolvanen , Steven Rostedt , Suren Baghdasaryan , Thomas Gleixner , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Valentin Schneider , Vincent Guittot , Vincenzo Frascino , Vlastimil Babka , Will Deacon , workflows@vger.kernel.org, x86@kernel.org Subject: [PATCH v8 09/27] mm/ksw: ignore false positives from exit trampolines Date: Tue, 11 Nov 2025 00:36:04 +0800 Message-ID: <20251110163634.3686676-10-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251110163634.3686676-1-wangjinchao600@gmail.com> References: <20251110163634.3686676-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1732040002 X-Stat-Signature: qr6js7u1ceb7xfu9zegb3kyzcw4cds9x X-HE-Tag: 1762792642-478348 X-HE-Meta: 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 gXPEQU4Q 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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 3817a172dc25..f922b4164be5 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 @@ -14,10 +15,46 @@ static DEFINE_MUTEX(all_wp_mutex); static ulong holder; +#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(); @@ -164,6 +201,7 @@ int ksw_watch_init(void) { int ret; + ksw_watch_resolve_trampoline(); ret = ksw_watch_alloc(); if (ret <= 0) return -EBUSY; -- 2.43.0