From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="lNBwJFoq" Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 84C1AD73 for ; Tue, 5 Dec 2023 10:29:48 -0800 (PST) Received: from pwmachine.numericable.fr (85-170-33-133.rev.numericable.fr [85.170.33.133]) by linux.microsoft.com (Postfix) with ESMTPSA id EB2F720B74C0; Tue, 5 Dec 2023 10:29:46 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com EB2F720B74C0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1701800987; bh=xFBQu+urMrliMCmn0RT32sID4f/zXlOoT3ftBiWYJts=; h=From:To:Cc:Subject:Date:From; b=lNBwJFoqN4E6nbjV4iPDj5e3Efhyp5NhWbQNBIQjH3ybre7zlzG9RnvETL1O8j6iZ 2JROWCXHy2cr+MmwuoE7f6ngBdgAD3Hcdns7x1qTrzdOlIo3X4G5Z3OCMzh0q2Xy6P BRmKoK/YtesYYJzAaDyZscvxbMNMCYTPVRsF5xE0= From: Francis Laniel To: stable@vger.kernel.org Cc: Greg KH , Francis Laniel , Masami Hiramatsu Subject: [PATCH 4.14.y 1/2] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols Date: Tue, 5 Dec 2023 19:29:22 +0100 Message-Id: <20231205182923.128898-1-flaniel@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit b022f0c7e404887a7c5229788fc99eff9f9a80d5 upstream. When a kprobe is attached to a function that's name is not unique (is static and shares the name with other functions in the kernel), the kprobe is attached to the first function it finds. This is a bug as the function that it is attaching to is not necessarily the one that the user wants to attach to. Instead of blindly picking a function to attach to what is ambiguous, error with EADDRNOTAVAIL to let the user know that this function is not unique, and that the user must use another unique function with an address offset to get to the function they want to attach to. Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/ Cc: stable@vger.kernel.org Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer") Suggested-by: Masami Hiramatsu Signed-off-by: Francis Laniel Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/ Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google) (cherry picked from commit b022f0c7e404887a7c5229788fc99eff9f9a80d5) --- kernel/trace/trace_kprobe.c | 48 +++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index d66aed6e9c75..45779ec370fa 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -617,6 +617,36 @@ static inline void sanitize_event_name(char *name) *name = '_'; } +struct count_symbols_struct { + const char *func_name; + unsigned int count; +}; + +static int count_symbols(void *data, const char *name, struct module *unused0, + unsigned long unused1) +{ + struct count_symbols_struct *args = data; + + if (strcmp(args->func_name, name)) + return 0; + + args->count++; + + return 0; +} + +static unsigned int number_of_same_symbols(char *func_name) +{ + struct count_symbols_struct args = { + .func_name = func_name, + .count = 0, + }; + + kallsyms_on_each_symbol(count_symbols, &args); + + return args.count; +} + static int create_trace_kprobe(int argc, char **argv) { /* @@ -746,6 +776,24 @@ static int create_trace_kprobe(int argc, char **argv) } argc -= 2; argv += 2; + if (symbol && !strchr(symbol, ':')) { + unsigned int count; + + count = number_of_same_symbols(symbol); + if (count > 1) + /* + * Users should use ADDR to remove the ambiguity of + * using KSYM only. + */ + return -EADDRNOTAVAIL; + else if (count == 0) + /* + * We can return ENOENT earlier than when register the + * kprobe. + */ + return -ENOENT; + } + /* setup a probe */ if (!event) { /* Make a new event name */ -- 2.34.1