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 2E90E16C87F; Mon, 22 Apr 2024 23:56:32 +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=1713830193; cv=none; b=JQevotxcdePz19kMtOFjRNhsv/HjgaOL+oagblJnXHA0F/yyFPnmOerUVDoBs3ldriDHPBVk+pgsdzlDckii2bT6pAcCLX6+qrpC02WLT6NzsZqoEekrZJnRELmiVugWvMBwwOcenzooNmG4aHdzEw0BWoivflitSrE42cgRD6U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713830193; c=relaxed/simple; bh=lYUVs8JnfKisT+vOBsyjwB8HONXYUY/m57L4D8/rw0Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QYka5vdhxtmnQFzvRlXajEyolmNV2IFI66emlkZLtfkk5vKA6tzV/YsAwbMdmpjmBzJGs3saRUoU5tWt48rmPPYln7hjgXVS0ZlF6rm28ODT0wdkY/pQRvU5ctylkGwlQTcw8iYz8hhWN9HPkpL55sJu7IMY9RCsfLrxnB7ajMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PuaLkRK5; 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="PuaLkRK5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9F38C2BD11; Mon, 22 Apr 2024 23:56:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713830192; bh=lYUVs8JnfKisT+vOBsyjwB8HONXYUY/m57L4D8/rw0Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PuaLkRK5XCf5VJn1uQbdzG2aU3cjAUJFo+37wjHdTUDiIBHAqQuEiKJ1L/DlKpsOU KXYCqIZjsooT6FgRr/l18N6/EVDn5EAofGLoLAuEHovfqCB/KNXG1YIqcS80KmGVk9 UnFRkDrVNoqGhbFevPp5J2tK1dNfPqfX3sPscg4Qwd5nUuFod6WB7spG59h/r14pKb pVuXlvnR002VYAxSINxQLdoZyjlX54yeR09NkTKgOgXZHA0hJ0tUhXLyTTkTKMOcms fN7KEYm7D2WdN7XNGbMwUUybdiXcxw0L/ZJXzh0HeuYsntsUKpXf5UBnPnH2sxU5Gj gLU0UVtSeREqQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Rik van Riel , Tejun Heo , Josef Bacik , Jens Axboe , Sasha Levin , cgroups@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 13/29] blk-iocost: avoid out of bounds shift Date: Mon, 22 Apr 2024 19:16:54 -0400 Message-ID: <20240422231730.1601976-13-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240422231730.1601976-1-sashal@kernel.org> References: <20240422231730.1601976-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.28 Content-Transfer-Encoding: 8bit From: Rik van Riel [ Upstream commit beaa51b36012fad5a4d3c18b88a617aea7a9b96d ] UBSAN catches undefined behavior in blk-iocost, where sometimes iocg->delay is shifted right by a number that is too large, resulting in undefined behavior on some architectures. [ 186.556576] ------------[ cut here ]------------ UBSAN: shift-out-of-bounds in block/blk-iocost.c:1366:23 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') CPU: 16 PID: 0 Comm: swapper/16 Tainted: G S E N 6.9.0-0_fbk700_debug_rc2_kbuilder_0_gc85af715cac0 #1 Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A23 12/08/2020 Call Trace: dump_stack_lvl+0x8f/0xe0 __ubsan_handle_shift_out_of_bounds+0x22c/0x280 iocg_kick_delay+0x30b/0x310 ioc_timer_fn+0x2fb/0x1f80 __run_timer_base+0x1b6/0x250 ... Avoid that undefined behavior by simply taking the "delay = 0" branch if the shift is too large. I am not sure what the symptoms of an undefined value delay will be, but I suspect it could be more than a little annoying to debug. Signed-off-by: Rik van Riel Cc: Tejun Heo Cc: Josef Bacik Cc: Jens Axboe Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20240404123253.0f58010f@imladris.surriel.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-iocost.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 7ee8d85c2c68d..a382b3a39820a 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1347,7 +1347,7 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; struct blkcg_gq *blkg = iocg_to_blkg(iocg); - u64 tdelta, delay, new_delay; + u64 tdelta, delay, new_delay, shift; s64 vover, vover_pct; u32 hwa; @@ -1362,8 +1362,9 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now) /* calculate the current delay in effect - 1/2 every second */ tdelta = now->now - iocg->delay_at; - if (iocg->delay) - delay = iocg->delay >> div64_u64(tdelta, USEC_PER_SEC); + shift = div64_u64(tdelta, USEC_PER_SEC); + if (iocg->delay && shift < BITS_PER_LONG) + delay = iocg->delay >> shift; else delay = 0; -- 2.43.0