From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f177.google.com (mail-pl1-f177.google.com [209.85.214.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 102432EBBA4 for ; Fri, 12 Sep 2025 10:12:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757671978; cv=none; b=ro0DXB0JCkD/aJU6sqhhu3pjPn/vu5HKlZTa9jAb1vxUtncFhzKdOcF9sheyjd7LavzfE+Rijp9yODdV4d8KOqk1I0+Ye/9B64wxu9nFcZemvEkxwp1boyjyLeUNa7asP12szcrwlTxIVsk/j5FAV95UHsjMASD7onrQqAtOyXs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757671978; c=relaxed/simple; bh=6mefF6IMMzyvYBUHPb6m4n0UB5fHQfdxvPTrHUmunyQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TxcI47Y/yFwl1VcvwFjfjJR8Nok1fOCkMoBVkaQLSOpJLAH6cKucFMKkfRq0ZbuV95uds+A8S6app5kfBMxrDpAzF7Lm320ru3hQM4hNs7it3G7sjYdkteXBLIHfaJEJJ8T/X9lu3qclXKNHZ9c3aIVQtGmfzcDue5cWxLij5+8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=PvO85rwF; arc=none smtp.client-ip=209.85.214.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PvO85rwF" Received: by mail-pl1-f177.google.com with SMTP id d9443c01a7336-244580523a0so17359265ad.1 for ; Fri, 12 Sep 2025 03:12:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1757671976; x=1758276776; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=mwBrRJrnxCqu1u7UrV9e609up8TstQr3mGzjgxeQ/fA=; b=PvO85rwFE+AFthnd22KtiyMXusH738r4OMXw2fZ9VzfnQrqCGup4UKQz5fYhdpFWYd Ffd0dZ/n7VafldJrABpQ55J9n+PB1T7eVmgnmHp+KNCkqZ9ZRk8ckq7DotHot6OY+IBg pCbpV/T5guQi0IH8QXNdaSt7xTNNuKC3gKJwl/u1fSrhI+6Vihi6STUgmfq0anhSqQAU HsqIqc618JiCafF0EgtDPY5F8JRpGqXEjBmSUvK/YPy3k98rXQ9jZ1N6cw4cZSFRlizi dXjRgM0HRsZEspTVExv7LgtV/KiSPYTMRt3ILK+wL9LWVLcY7XtBHRfUwdkDyzW3jBHu hiHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757671976; x=1758276776; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=mwBrRJrnxCqu1u7UrV9e609up8TstQr3mGzjgxeQ/fA=; b=h/zFd4fb//+9smqW+QgxTFklAo+oo/FL1YtQwC2tzHvzPQk5Bt9sppAUTwg6P4X+ui opykXM2GjXbOk1S2hQNXHyG4qtkdhmmfO9c2Lb/v3miiMQSveK0LaKRIqGpQGFQ/1wKx yHnik9xlF2sKlwG6ewGc4XUYaXwMJiSng4Boz4D6MsuHU5OzF4CsRJahMv/nmvOPEeX2 R72aiBoGHlApX4atr4rxwTufIeZWf4uUh3EjG25SLXVbDBM8AvzUUuqYLGmBSSLfEwsd dnMWq8kX+fGdALHSP3JyVTrINRyzi6Yr4j886C5lOQSZM/bbKNwiJ0WnuaeY3stH1Doz t3zQ== X-Forwarded-Encrypted: i=1; AJvYcCWnYsDgfmQ4FObmeBReRnq+FciRiXw2MljkAwEBb6iLovZTkyEJ+9gSYeAYNwXQ3oIfBSFJ+Tq67XqG6Le2Le7pmB8=@vger.kernel.org X-Gm-Message-State: AOJu0YxD9QvxAoiNhwKMAgQdnfMWLZ6htQekZhEfpK37TArEUe9xYHh/ MsflZls+3y8hqjrmVoMK1ouBf4+BrL1y/nChab1sVV7ziXml7/ucrlP2 X-Gm-Gg: ASbGnctp5ArkzvNrpBUViIYguxbYUjmnWRdrWsEQEeygdOqWgSpWgNi+z4iDivKAVib BF7OMorKHf9w5Szbjjkqp2rIRfZgRl08psT/gKwaqs/rhEDvrUhHqmr7+nhYoeRa+HE7rE3VN4R 292MEvuT/dUhH9SmdZh6bw/jJWypGMYKdc3x2KjwIw2tyuZLnm+MaEY+CYp6HHfWY/7ik0ABsu4 esHlNJ64x063ypudKKnrrb7M+McaP4BiNaG7nsXZI6aVyPhew/jpqWnkJrrJGEx5ToxlBD4k8f+ OCrhnUU5waD/GKQTYoiT2fkpOGR65Zt02y/X6/dKn/vd7ugGqbWtvjNd4V3FzqYNC+274iHRnEW kldCWUGD1VvJVXoemXf0wShdJxv9IdBtNK4NdAh0= X-Google-Smtp-Source: AGHT+IHmhDxbrAgWt/ZFf2b2ARujdiSrTzk9h/pJ/Apo0LVYSifl646MIHmgwZB8g3f29HVWj78WGw== X-Received: by 2002:a17:903:2f0d:b0:248:79d4:93bb with SMTP id d9443c01a7336-25d26e449b9mr26345655ad.31.1757671976359; Fri, 12 Sep 2025 03:12:56 -0700 (PDT) Received: from localhost ([185.49.34.62]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-25c36cc6af7sm44843015ad.5.2025.09.12.03.12.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Sep 2025 03:12:55 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Kees Cook , Alice Ryhl , Sami Tolvanen , Miguel Ojeda , Masahiro Yamada , Rong Xu , Naveen N Rao , David Kaplan , Andrii Nakryiko , Jinjie Ruan , Nam Cao , workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, Andrey Ryabinin , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, "David S. Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v4 12/21] mm/ksw: resolve stack watch addr and len Date: Fri, 12 Sep 2025 18:11:22 +0800 Message-ID: <20250912101145.465708-13-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250912101145.465708-1-wangjinchao600@gmail.com> References: <20250912101145.465708-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add helpers to find the stack canary or a local variable addr and len for the probed function based on ksw_get_config(). For canary search, limits search to a fixed number of steps to avoid scanning the entire stack. Validates that the computed address and length are within the kernel stack. Signed-off-by: Jinchao Wang --- mm/kstackwatch/stack.c | 88 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 84 insertions(+), 4 deletions(-) diff --git a/mm/kstackwatch/stack.c b/mm/kstackwatch/stack.c index ac52a9f81486..65a97309e028 100644 --- a/mm/kstackwatch/stack.c +++ b/mm/kstackwatch/stack.c @@ -9,18 +9,98 @@ #include "kstackwatch.h" +#define INVALID_PID -1 +#define MAX_CANARY_SEARCH_STEPS 128 static struct kprobe entry_probe; static struct fprobe exit_probe; -#define INVALID_PID -1 static atomic_t ksw_stack_pid = ATOMIC_INIT(INVALID_PID); +static unsigned long ksw_find_stack_canary_addr(struct pt_regs *regs) +{ + unsigned long *stack_ptr, *stack_end, *stack_base; + unsigned long expected_canary; + unsigned int i; + + stack_ptr = (unsigned long *)kernel_stack_pointer(regs); + + stack_base = (unsigned long *)(current->stack); + + // TODO: limit it to the current frame + stack_end = (unsigned long *)((char *)current->stack + THREAD_SIZE); + + expected_canary = current->stack_canary; + + if (stack_ptr < stack_base || stack_ptr >= stack_end) { + pr_err("Stack pointer 0x%lx out of bounds [0x%lx, 0x%lx)\n", + (unsigned long)stack_ptr, (unsigned long)stack_base, + (unsigned long)stack_end); + return 0; + } + + for (i = 0; i < MAX_CANARY_SEARCH_STEPS; i++) { + if (&stack_ptr[i] >= stack_end) + break; + + if (stack_ptr[i] == expected_canary) { + pr_debug("canary found i:%d 0x%lx\n", i, + (unsigned long)&stack_ptr[i]); + return (unsigned long)&stack_ptr[i]; + } + } + + pr_debug("canary not found in first %d steps\n", + MAX_CANARY_SEARCH_STEPS); + return 0; +} + +static int ksw_stack_validate_addr(unsigned long addr, size_t size) +{ + unsigned long stack_start, stack_end; + + if (!addr || !size) + return -EINVAL; + + stack_start = (unsigned long)current->stack; + stack_end = stack_start + THREAD_SIZE; + + if (addr < stack_start || (addr + size) > stack_end) + return -ERANGE; + + return 0; +} + static int ksw_stack_prepare_watch(struct pt_regs *regs, const struct ksw_config *config, ulong *watch_addr, u16 *watch_len) { - /* implement logic will be added in following patches */ - *watch_addr = 0; - *watch_len = 0; + ulong addr; + u16 len; + + /* Resolve addresses for all active watches */ + switch (ksw_get_config()->type) { + case WATCH_CANARY: + addr = ksw_find_stack_canary_addr(regs); + len = sizeof(unsigned long); + break; + + case WATCH_LOCAL_VAR: + addr = kernel_stack_pointer(regs) + + ksw_get_config()->local_var_offset; + len = ksw_get_config()->local_var_len; + break; + + default: + pr_err("Unknown watch type %d\n", ksw_get_config()->type); + return -EINVAL; + } + + if (ksw_stack_validate_addr(addr, len)) { + pr_err("invalid stack addr:0x%lx len :%u\n", addr, len); + return -EINVAL; + } + + *watch_addr = addr; + *watch_len = len; return 0; } -- 2.43.0