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 1043A7263B; Sat, 7 Jun 2025 16:07:10 +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=1749312430; cv=none; b=TK+4peg7EkmJo/TDY+OxdUz6saFByZIcUuzP8KLlSe3aRks700QfhFbRdI3aBxwu1/x56T9GpotJdzcWWFp3em4f19w40Yj9arAERq8blgirjyPSM3wUvtgedLl0+fgHBeiA8TYjvgauf2Qf0OrJNpP3WTxsVpYdkNBGgphSfmQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749312430; c=relaxed/simple; bh=jH5iUK/ZumuFL9SJdUxHayX4sw9/fNOOcHbgrmRExC8=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=bSLa4Ai4jamjt8ShQo9PoVfKtnvoYEVQb/9/A9w9pcEkIF7900/KybasOqCQoQKEZXF6iV13ixoroGkDpPZUfQonpqE/W85cm6KkN837FUTL1eh56w6b2GUap8xaj+XkTerDWHeANpg7CPMDt3WBhIcJDNgLxrLhGZvXicBAgzk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NPVmn9u4; 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="NPVmn9u4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDBC6C4CEF1; Sat, 7 Jun 2025 16:07:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749312429; bh=jH5iUK/ZumuFL9SJdUxHayX4sw9/fNOOcHbgrmRExC8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=NPVmn9u49+6AsLKBu8MXeUh9jJYneCr1DfiukdrLZwlHamiEqk0sLfegXqYCu/nD+ Zp7SpdhBGI86Tkcoa0NrCa0pSYQC5liDuOcT+MtXYMj16o301jTg0ISNuTUbMkTAD1 Jsuv8nSnBlcH+5ZNrmjI+Uv70YTkiQ6pZF51cJxGcsWsYnCDbDMOiALBwgRyF/q9UK DSGGe5P/o8HAb2LT8BrURiuDRkSMLzUQIBuu+5OZl4NrVMOaLelf7uWJfhqsFVK2LP +141J2wqnU40IxzNokL5usqPM8N9ZsmgX1pM6165u2EE9fQEEauZavtnWciWP3Zd1c MwgtHtL/C560g== Date: Sat, 7 Jun 2025 17:07:03 +0100 From: Jonathan Cameron To: Sean Nyekjaer Cc: David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] iio: accel: fxls8962af: Fix use after free in fxls8962af_fifo_flush Message-ID: <20250607170703.3fab39e9@jic23-huawei> In-Reply-To: <5zdrnf75n2nfuk3bjzynnj2b57fkptk3lltjf4xaloxorzk27w@6qwdcn5tfynz> References: <20250603-fxlsrace-v2-1-5381b36ba1db@geanix.com> <5zdrnf75n2nfuk3bjzynnj2b57fkptk3lltjf4xaloxorzk27w@6qwdcn5tfynz> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.48; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 03 Jun 2025 13:36:15 +0000 Sean Nyekjaer wrote: > On Tue, Jun 03, 2025 at 08:29:51AM +0100, David Lechner wrote: > > On 6/3/25 7:25 AM, Sean Nyekjaer wrote: > > > fxls8962af_fifo_flush() uses indio_dev->active_scan_mask (with > > > iio_for_each_active_channel()) without making sure the indio_dev > > > stays in buffer mode. > > > There is a race if indio_dev exits buffer mode in the middle of the > > > interrupt that flushes the fifo. Fix this by calling > > > synchronize_irq() to ensure that no interrupt is currently running when > > > disabling buffer mode. > > > > > > Unable to handle kernel NULL pointer dereference at virtual address 00000000 when read > > > [...] > > > _find_first_bit_le from fxls8962af_fifo_flush+0x17c/0x290 > > > fxls8962af_fifo_flush from fxls8962af_interrupt+0x80/0x178 > > > fxls8962af_interrupt from irq_thread_fn+0x1c/0x7c > > > irq_thread_fn from irq_thread+0x110/0x1f4 > > > irq_thread from kthread+0xe0/0xfc > > > kthread from ret_from_fork+0x14/0x2c > > > > > > Fixes: 79e3a5bdd9ef ("iio: accel: fxls8962af: add hw buffered sampling") > > > Cc: stable@vger.kernel.org > > > Suggested-by: David Lechner > > > Signed-off-by: Sean Nyekjaer > > > --- > > > Changes in v2: > > > - As per David's suggestion; switched to use synchronize_irq() instead. > > > - Link to v1: https://lore.kernel.org/r/20250524-fxlsrace-v1-1-dec506dc87ae@geanix.com > > Were you able to find a way to reproduce the bug well enough to > > test this? > > > > Yeah. Sorry I didn't included the reproducer :) > > I added: > diff --git a/drivers/iio/accel/fxls8962af-core.c b/drivers/iio/accel/fxls8962af-core.c > index f2558fba491d..ce9a14245f83 100644 > --- a/drivers/iio/accel/fxls8962af-core.c > +++ b/drivers/iio/accel/fxls8962af-core.c > @@ -1040,6 +1040,8 @@ static irqreturn_t fxls8962af_interrupt(int irq, void *p) > unsigned int reg; > int ret; > > + usleep_range(10000, 15000); > + > ret = regmap_read(data->regmap, FXLS8962AF_INT_STATUS, ®); > if (ret) > return IRQ_NONE; > > And it was reproduceable within 10 secs: > root@localhost:/sys/bus/iio/devices/iio:device0/buffer0# > while true; do echo 1 > enable; sleep 1; echo 0 > enable; sleep 1; done > > With synchronize_irq(data->irq); I have not been able to reproduce it. Nice. Applied to a temporary tree that I'll rebase on rc1 once available. Thanks, Jonathan > > /Sean >