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 A6E657E0 for ; Tue, 26 Jul 2022 08:06:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5999C36AE5; Tue, 26 Jul 2022 08:06:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1658822804; bh=AuSXlGXkPcDkuhy4cIR2vtHDpg/jer5nbJzf7kZ8fcg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RCCcqAC2M4GslsUvGs5C1x4+/2G3a3w3bEuNTAsrTHtM9sH6pN3U++bWLhLWuMidi zyAWadDpmrSgL3lkX4NJrljlmQzjsXQeXb0RJ3rAOeqYMNes0+jhfEafI+YcAXukfV Cb+GkC9NUF1my0VIXuNvFzzLy4cZ13h4wg8V6FlXp3svHe1+70jkp9K9CouDzXWvoE 82aN/TJUjy7zVRKWMxIiI5Ke8jDreKJX0p7iWbhun3lHl67Do4z9E+1wMqXTfhLOS2 W2LC0sskVe1kYmIVXoAMYvs01+RLxH6s7V76IQE4clsmRJLHP1AwakVhf3OnsjtjV9 NQF6jaLu8+bCA== Date: Tue, 26 Jul 2022 13:36:36 +0530 From: Manivannan Sadhasivam To: Qiang Yu Cc: quic_hemantk@quicinc.com, loic.poulain@linaro.org, quic_jhugo@quicinc.com, mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, quic_cang@quicinc.com, ath11k@lists.infradead.org, kvalo@kernel.org Subject: Re: [PATCH v3 1/1] bus: mhi: host: Fix up null pointer access in mhi_irq_handler Message-ID: <20220726080636.GE5522@workstation> References: <1658459838-30802-1-git-send-email-quic_qianyu@quicinc.com> Precedence: bulk X-Mailing-List: mhi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1658459838-30802-1-git-send-email-quic_qianyu@quicinc.com> User-Agent: Mutt/1.9.4 (2018-02-28) +ath11k, Kalle On Fri, Jul 22, 2022 at 11:17:18AM +0800, Qiang Yu wrote: > The irq handler for a shared IRQ ought to be prepared for running > even now it's being freed. So let's check the pointer used by > mhi_irq_handler to avoid null pointer access since it is probably > released before freeing IRQ. > > Signed-off-by: Qiang Yu Reviewed-by: Manivannan Sadhasivam Thanks, Mani > --- > v2->v3: add comments > v1->v2: change dev_err to dev_dbg > > drivers/bus/mhi/host/main.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c > index f3aef77a..df0fbfe 100644 > --- a/drivers/bus/mhi/host/main.c > +++ b/drivers/bus/mhi/host/main.c > @@ -430,12 +430,25 @@ irqreturn_t mhi_irq_handler(int irq_number, void *dev) > { > struct mhi_event *mhi_event = dev; > struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl; > - struct mhi_event_ctxt *er_ctxt = > - &mhi_cntrl->mhi_ctxt->er_ctxt[mhi_event->er_index]; > + struct mhi_event_ctxt *er_ctxt; > struct mhi_ring *ev_ring = &mhi_event->ring; > - dma_addr_t ptr = le64_to_cpu(er_ctxt->rp); > + dma_addr_t ptr; > void *dev_rp; > > + /* > + * If CONFIG_DEBUG_SHIRQ is set, the IRQ handler will get invoked during __free_irq() > + * and by that time mhi_ctxt() would've freed. So check for the existence of mhi_ctxt > + * before handling the IRQs. > + */ > + if (!mhi_cntrl->mhi_ctxt) { > + dev_dbg(&mhi_cntrl->mhi_dev->dev, > + "mhi_ctxt has been freed\n"); > + return IRQ_HANDLED; > + } > + > + er_ctxt = &mhi_cntrl->mhi_ctxt->er_ctxt[mhi_event->er_index]; > + ptr = le64_to_cpu(er_ctxt->rp); > + > if (!is_valid_ring_ptr(ev_ring, ptr)) { > dev_err(&mhi_cntrl->mhi_dev->dev, > "Event ring rp points outside of the event ring\n"); > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project. >