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 18FC737DAAE; Sun, 9 Aug 2026 02:32:17 +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=1786242738; cv=none; b=IcjbPmYJzhqEatqRyj533A01BXPHxvMpSjQ6mlOWKYJUKGmlMHbn9O/GDcU6iSCQ1j/1Myvsws68UC9ossi7fzDEoUzVGOZk35TTW3zu5o7fYWF3AV/uCBiZuunxEANUQo9HKVV0Y3i+8WIkgJflf+Wwbj5/IuxOnQX2wBcFYa0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786242738; c=relaxed/simple; bh=qYArbJM/Ky7ieTV7mLSRd5w7dIPe9cHsHZQxM03DSE8=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=EZCmVOf95W84pq4mNA/ZLb5ypU3eKiUzpEOBBCsTo1bzZLiy5dkdC5r8LQZjsjOn9HntySr0TJgRWD44dmgGylrBRr8W5tvJGvaIcodDPGHcQqv9H11o0ODK1oZw26M0vLzbTvXomCymspjwEPLMDfmQEflXMOxd2njf30os/Vg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Lu1llMDC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Lu1llMDC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F6EF1F00AC4; Sun, 9 Aug 2026 02:32:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786242736; bh=pTR46X70duIEW3e4MGyPdQ0CYj/oUx/vVN7OebHihLA=; h=Date:From:To:Cc:Subject:References; b=Lu1llMDCrCUI4g0Ew1KuH9XWoDj8v32ATCJVUKm6Mhghi2OxdTmtRGiV6ALzfNSMm qhIxe/K7AE9DVT81uPNGhoXddk3YMHRUgz+EvK3+9CDDUJfGovWJGjBVhoTNIKqrSY ko9ZUg3mYYfdMl36qidsRSxDwgmltW0BkclYas7wDsuwxIzGDbj888PpVjgdCD8T0x DcSw8IOvrs4lPv9ZbdEVwlI/gmk3peXeAnd0TECXJ+PXrkh+A1Ua4FNvjmPEj1M9V0 TKk/iEUI+fjtav+PJo3dcUvF/NX5BF1J1VZeI4gJTz+jPQjU1mxukSNEeOBeuM1wle w/B775sj0uLiw== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wstKo-00000001N6C-2fxo; Sat, 08 Aug 2026 22:32:22 -0400 Message-ID: <20260809023222.497514011@kernel.org> User-Agent: quilt/0.69 Date: Sat, 08 Aug 2026 22:31:52 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Josh Poimboeuf Subject: [for-linus][PATCH 08/12] ftrace: Fix off-by-one fentry site disable in ftrace_free_mem() References: <20260809023144.852271250@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Josh Poimboeuf 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 --- kernel/trace/ftrace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 414e425c2d80..7c50f8ae5a0c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -8305,7 +8305,8 @@ static void add_to_clear_hash_list(struct list_head *clear_list, 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; @@ -8315,6 +8316,9 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) 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 */ -- 2.53.0