linux-kernel - [PATCH v5 09/23] mm/ksw: ignore false positives from exit trampolines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250924115124.194940-10-wangjinchao600@gmail.com>
Date: Wed, 24 Sep 2025 19:50:52 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Rapoport <rppt@...nel.org>,
	Alexander Potapenko <glider@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Jonathan Corbet <corbet@....net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	David Hildenbrand <david@...hat.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Kees Cook <kees@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Rong Xu <xur@...gle.com>,
	Naveen N Rao <naveen@...nel.org>,
	David Kaplan <david.kaplan@....com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Jinjie Ruan <ruanjinjie@...wei.com>,
	Nam Cao <namcao@...utronix.de>,
	workflows@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org,
	linux-mm@...ck.org,
	llvm@...ts.linux.dev,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	kasan-dev@...glegroups.com,
	"David S. Miller" <davem@...emloft.net>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-trace-kernel@...r.kernel.org
Cc: Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v5 09/23] mm/ksw: ignore false positives from exit trampolines

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 <wangjinchao600@...il.com>
---
 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 <linux/cpuhotplug.h>
+#include <linux/ftrace.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/irqflags.h>
 #include <linux/mutex.h>
@@ -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