From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f174.google.com (mail-pf1-f174.google.com [209.85.210.174]) (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 BE9532E9EC2 for ; Thu, 9 Oct 2025 10:58:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760007485; cv=none; b=N8oA12BKcdv+0Ivby+fGSykT5tKerKsj1eshN6c9b/3v+Zeug9H0RESp8G9+kGl77w9hebedwM4NOz3WFUCZ+rYFcLrEmaBEnduNIt8QNyu26KGT5rN0lEB3C2WOQlnFyLuKSAYgCfLdQPyoIjHHCVsDND1jEI6dBx0GRSEUXJg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760007485; c=relaxed/simple; bh=ye1IFedT6QyfAsl7NnFp/ScKqi80nwnk9udpC+1GQaI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ISnSWqdS0OpPUC9YjN6wAbhV7QLC5g4bwET4bmzS/ybfwFbhEAz+3s2XFmrckAauzI+fKNEmOxEJRR4tbI3WuPDihGJbW20M1OoqOtCZotyMO01CVPyJ1Z7NSP4HGUsx4MUCpwcDjshKZxfKEqGEMmgdu1wkF70a2wDLeaVTUic= 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=LdKRLbWe; arc=none smtp.client-ip=209.85.210.174 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="LdKRLbWe" Received: by mail-pf1-f174.google.com with SMTP id d2e1a72fcca58-781010ff051so593460b3a.0 for ; Thu, 09 Oct 2025 03:58:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1760007483; x=1760612283; 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=1RtyZdLa/V9peD4vyIt7vF3g+yVd+tHG9wNYuCcZNH8=; b=LdKRLbWeg/b5DVlAqapHePmhvK9AG0yeiBom5D9bMCoIXu8P8c+Umy4sT7Kah1pDbI e1Rcp9JcDySTjznRdaxIei5/6B5nvO6zCKs+nDWrNiSPrNGqrdeTWCZv7Cu19ecN0mhe hZH3WFQTCOJJD1nTm7vvBdsNvVjxR2ln2aeSjGkELI7oeB379UefLEDPhsuQc0Hzx3Ta 26DCv+2k5pRPudddjUObqT4W6QcbK+ux/K3Z6CBv3WK9eyIOKaqTTkLC8xmMkbWLQeNN kcIxQfdmxd3mDrgLy84H4OnGKkhX6Ct46oqGyW3u5jrdmjedHtSOaMjBjM9dmINe8BSe jNLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760007483; x=1760612283; 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=1RtyZdLa/V9peD4vyIt7vF3g+yVd+tHG9wNYuCcZNH8=; b=I5iA6JBGV3SqSoGAMsQ80lIkCd0nlvG/wiRSL297mkyOt615XGzDs02d+D1bU3nd1I mSdj76nBkryKAJHetfxM6SbSXFbMdRV+ru/JCfo9xeAK7I0/UNdp226bBcmsLKx3/QQS DPT2i/8aJ1w02gKQqIBm8JwQo7RiYcTtTl5D6shL/wdKRCebIJcxnrRwWaFCCAYcqeFc D0knqTM6W2eUgpYzoicC4hoLwqVi90wJ2wMLP9rPV/3lnvKbCwM7nNwg+OVdYKIW2wDa 2H7T5tM8YEbSFj/pLVLVozUKhLgK1L6jA5SitsoBY3iKeSXpN5s8nWlGpgxVbBfTASPm 8A6g== X-Forwarded-Encrypted: i=1; AJvYcCWFJv8Y+aboe/p9FrkUOESDH0hrh6XA8xkxmk2MciuPntCHkzKoiLwTN45loCGMWEJgixgbbhQWdOrhE/zTpKUUEuc=@vger.kernel.org X-Gm-Message-State: AOJu0YylBYSie7GinLjzrRRI1lmTL1tY5nTjeG736digmB2HNPFU/zJp sn6aOgkjHBVntxb6RzaT/tBkYReXW7nUgfpxo+s8NNRegoaAqFTPVz19 X-Gm-Gg: ASbGncvzMmF5GF4Y5YbMY3Kb+x+hklFSNoGrHDJeEIkg9FYtxy8addiiSdCWv5/c8a4 EFe46OmmkuHPJORfxhBNf+HmATBhGYV3grRuWZyc4G9Idq+sUu3v+EL65dCQin3HABJ9GsIW/oL FvnURZfZFyH2SlWAzr4a1/gzdXvy7wFE9IM6BPSXkH8WZAcAYxf+P3M2/hb05Il2eUYMymnkRiM L6xXKbFJvZPBjrBIU+ldfx3HhZqQqDJfmUkMUBVef0CwtYTiiXUBaGhsMbueA0jVSyEqbNfG8sZ h6g3nwyB7zdo+CgRQs3dGjUXyNOHlf6lMcaiJWAxKNbuN8J3o+EOtShY1R2MEMa0iGlQCNY/KT2 dFaOZaT7J15JAAlTHTOzppR3IexThoD0wWCQFU+R2xdFTtscPhFhXCnBbSgFpFWip3/tLLgQ= X-Google-Smtp-Source: AGHT+IGV1mxHWu3pQaxCo2GAVbKHGeNdLDqI1po/b05L3G5Ejn51+25jeUHtC8qpbOYN5GwS7DtIXA== X-Received: by 2002:a05:6a20:12cd:b0:2f8:4558:ad9e with SMTP id adf61e73a8af0-32da839ee26mr9375118637.33.1760007482826; Thu, 09 Oct 2025 03:58:02 -0700 (PDT) Received: from localhost ([45.142.165.62]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b6099f3b041sm20711876a12.24.2025.10.09.03.58.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Oct 2025 03:58:02 -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. 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 v7 14/23] mm/ksw: resolve stack watch addr and len Date: Thu, 9 Oct 2025 18:55:50 +0800 Message-ID: <20251009105650.168917-15-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> 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 | 77 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 74 insertions(+), 3 deletions(-) diff --git a/mm/kstackwatch/stack.c b/mm/kstackwatch/stack.c index e596ef97222d..3c4cb6d5b58a 100644 --- a/mm/kstackwatch/stack.c +++ b/mm/kstackwatch/stack.c @@ -9,6 +9,7 @@ #include "kstackwatch.h" +#define MAX_CANARY_SEARCH_STEPS 128 static struct kprobe entry_probe; static struct fprobe exit_probe; @@ -59,13 +60,83 @@ static bool ksw_stack_check_ctx(bool entry) return false; } +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; + + // default is to watch the canary + if (!ksw_get_config()->watch_len) { + addr = ksw_find_stack_canary_addr(regs); + len = sizeof(ulong); + } else { + addr = kernel_stack_pointer(regs) + ksw_get_config()->sp_offset; + len = ksw_get_config()->watch_len; + } + + 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