From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4EBEB3803E9; Thu, 20 Aug 2026 15:13:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787238837; cv=none; b=dzc86NwJ/XsbZ/vZKnz4MIAIQf8NamVKXFNzyZ1pHgjyLOY1pxdtWMmMZXtGwUGkskdIT6+QGqi6FtFyc14KPDkhebxTDkPafrOceV5WyHN5vGrQylW9nwWwOZomEZKPQn3Ak1mtRGnU8lAh6UQoRrePJ8C85u7JlOzAKODO9KY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787238837; c=relaxed/simple; bh=j0URh4FM6ijZCgupvfYxlgNWTrhbVJacg/Zp0rQzMZM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=X7rAEGugjzFgF3e52Ciryb37dS09sIoccyqF4bRnyMvDk6O/M9MBHn387nBa090vlkmNzIAm0+2Qr4V/jP8yvMAsALdUttc9igP9cSLAJ10zomWt/U2ECgE5MbLPT6ucYE7PB33TV6CGpBxnH6rn9PQ3VaRli3qGLcoNwLguHKc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZDstkDyq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ZDstkDyq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA8051F000E9; Thu, 20 Aug 2026 15:13:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787238836; bh=pQPYc0k2ZIVn4hAVbz3PJHxKKwq1Iy/FAJaYjlCXOs8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZDstkDyqF+8s+tk8YrJ6KygIymLkuEAZ9JhPOZM9TqFfUhN71lxwHbqGHnwwjLS1r onMy3ODyEUJ/+RN0UsoFNVoLIhj7X66OwC4iH/F9jS8EZSPOvNrSq6oucvz1WwqRL0 ipxb4PN5w2jGy/hUbpPixfSrmQ/3q8w26l8AX2r4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josh Poimboeuf , "Masami Hiramatsu (Google)" , Steven Rostedt Subject: [PATCH 6.18 058/217] ftrace: Fix off-by-one fentry site disable in ftrace_free_mem() Date: Thu, 20 Aug 2026 16:53:46 +0200 Message-ID: <20260820145239.367068935@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145237.531699751@linuxfoundation.org> References: <20260820145237.531699751@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf commit 8b8292d6487c81bd57c2605a9b404b1cf8f1edfb upstream. When a module's init text is freed, do_init_module() calls ftrace_free_mem() with a half-open [start, end) range. However the ftrace_cmp_recs() comparator treats the upper bound as inclusive, as all its other users do, passing 'ip + size - 1'. So ftrace_free_mem() can delete a record sitting exactly at 'end', which is outside the freed range. For a kernel without CFI or IBT, the first record of a function is at the function start, which for the first function in a module is also the base of its text allocation. As the module allocator packs its regions, that address is often the 'end' passed by a neighboring module's do_init_module(), causing the first function's ftrace location to get disabled, preventing an attempt to livepatch it: livepatch: failed to find location for function 'pcspkr_probe' Convert the exclusive end to the inclusive 'end - 1' the comparator expects, and return early for an empty range to avoid the subtraction from underflowing when the init text size is zero. Cc: stable@vger.kernel.org Fixes: 42c269c88dc1 ("ftrace: Allow for function tracing to record init functions on boot up") Link: https://patch.msgid.link/1b5ccfa8095bdb1277f84af1c2c2e2205aca03ae.1785992188.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ftrace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7864,7 +7864,8 @@ static void add_to_clear_hash_list(struc void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) { unsigned long start = (unsigned long)(start_ptr); - unsigned long end = (unsigned long)(end_ptr); + /* end is inclusive and end_ptr is exclusive */ + unsigned long end = (unsigned long)(end_ptr) - 1; struct ftrace_page **last_pg = &ftrace_pages_start; struct ftrace_page *tmp_page = NULL; struct ftrace_page *pg; @@ -7874,6 +7875,9 @@ void ftrace_free_mem(struct module *mod, struct ftrace_init_func *func, *func_next; LIST_HEAD(clear_hash); + if (start_ptr >= end_ptr) + return; + key.ip = start; key.flags = end; /* overload flags, as it is unsigned long */