From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA4111E87B; Mon, 31 Mar 2025 15:35:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743435340; cv=none; b=r+vMl6xzri5+Afz4eVLhLMHJqpVjl7rNpFtpgnBvLprS5FukKYu/pBkk1IbkIbRVIUBL5KKrn7pSW/0jJtODup/sOh5/DqYTFGyiKbHNpKRILiZwl1LaoSeLXIqpVBvCyrce6mA1vFNAIxazYv8YkeN+3cOGrONWhNLk3YXg0PU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743435340; c=relaxed/simple; bh=XfxUmWlDoXAenKpS0CquwXTLrNbsbqfRSmcog6/7CvM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=qAZvPK/CC6MTYEea7Bk8fOSw1EAB3x4J1mY7hybwO6UxLtfnfDoNgnrkG7O8VvCnSlB2FU6jiIYlphvUEZ1WFsRu6muW3oouk7xcX8deNNS5+KluuIYQTIKDPyHULf+h5Be1mQSjrNGwDZS9GVKMtYNJQM/peCBgVBoM4QljgTU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KbBFnhx7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KbBFnhx7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AD07C4CEE3; Mon, 31 Mar 2025 15:35:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743435339; bh=XfxUmWlDoXAenKpS0CquwXTLrNbsbqfRSmcog6/7CvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KbBFnhx7RU1dsjDDTXm6RfyBot0/Tl0E+NcECfT+04AArRxNETUcyzCOhhebhkySN FGMePSypqVb2U3dGIP06TACMS3wWR9eNK4ZVXio+BgwyAvRkSBdKz9QVBD/Kkic3Kv BzOL+0rhxnGDTbMhlMEQOx+V0Blkdnt1Y+8pxaclFpW+3a6Tq9AiJ+j5HvVCIYxTFZ N2/ZPuKulKvL9Hb2ZvsA9n891YzIb6CpzSnnVecbcmYSK3kodMeEoaKanw36QWMGzw Yln1Sw6UW1uW5r2hE9ep2NT3QIfcd72H2oxaUpwJkrL7yN3HjxhvxBf06PFvDIfJeN FTlgCHGwvFTvA== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Masami Hiramatsu , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v2 1/7] tracing: fprobe events: Fix possible UAF on modules Date: Tue, 1 Apr 2025 00:35:36 +0900 Message-ID: <174343533593.843280.8788277038071990492.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <174343532655.843280.15317319860632975273.stgit@devnote2> References: <174343532655.843280.15317319860632975273.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit From: Masami Hiramatsu (Google) Commit ac91052f0ae5 ("tracing: tprobe-events: Fix leakage of module refcount") moved try_module_get() from __find_tracepoint_module_cb() to find_tracepoint() caller, but that introduced a possible UAF because the module can be unloaded before try_module_get(). In this case, the module object should be freed too. Thus, try_module_get() does not only fail but may access to the freed object. To avoid that, try_module_get() in __find_tracepoint_module_cb() again. Fixes: ac91052f0ae5 ("tracing: tprobe-events: Fix leakage of module refcount") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_fprobe.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index 985ff98272da..2cd9ff1049f1 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -919,9 +919,15 @@ static void __find_tracepoint_module_cb(struct tracepoint *tp, struct module *mo struct __find_tracepoint_cb_data *data = priv; if (!data->tpoint && !strcmp(data->tp_name, tp->name)) { - data->tpoint = tp; - if (!data->mod) + /* If module is not specified, try getting module refcount. */ + if (!data->mod && mod) { + /* If failed to get refcount, ignore this tracepoint. */ + if (!try_module_get(mod)) + return; + data->mod = mod; + } + data->tpoint = tp; } } @@ -933,7 +939,11 @@ static void __find_tracepoint_cb(struct tracepoint *tp, void *priv) data->tpoint = tp; } -/* Find a tracepoint from kernel and module. */ +/* + * Find a tracepoint from kernel and module. If the tracepoint is on the module, + * the module's refcount is incremented and returned as *@tp_mod. Thus, if it is + * not NULL, caller must call module_put(*tp_mod) after used the tracepoint. + */ static struct tracepoint *find_tracepoint(const char *tp_name, struct module **tp_mod) { @@ -962,7 +972,10 @@ static void reenable_trace_fprobe(struct trace_fprobe *tf) } } -/* Find a tracepoint from specified module. */ +/* + * Find a tracepoint from specified module. In this case, this does not get the + * module's refcount. The caller must ensure the module is not freed. + */ static struct tracepoint *find_tracepoint_in_module(struct module *mod, const char *tp_name) { @@ -1169,11 +1182,6 @@ static int trace_fprobe_create_internal(int argc, const char *argv[], if (is_tracepoint) { ctx->flags |= TPARG_FL_TPOINT; tpoint = find_tracepoint(symbol, &tp_mod); - /* lock module until register this tprobe. */ - if (tp_mod && !try_module_get(tp_mod)) { - tpoint = NULL; - tp_mod = NULL; - } if (tpoint) { ctx->funcname = kallsyms_lookup( (unsigned long)tpoint->probestub,