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Thu, 09 Oct 2025 03:57:42 -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 v7 09/23] mm/ksw: ignore false positives from exit trampolines Date: Thu, 9 Oct 2025 18:55:45 +0800 Message-ID: <20251009105650.168917-10-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251009105650.168917-1-wangjinchao600@gmail.com> References: <20251009105650.168917-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 6D7401C0004 X-Stat-Signature: oakippjf6mzkqywrtjsnwncqwzbazqk4 X-HE-Tag: 1760007464-862319 X-HE-Meta: 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 URdr12GZ 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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