From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 69089CA5FA2 for ; Mon, 28 Sep 2026 13:12:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=AFOBGkbyLEsT8oHbnv3Tx7r5hqOModam36oOeO/AXUQ=; b=TC4JxCUnse82uZIgOwMAWoy4me 3cC0dCQuowTZieMJkOThtGouXmh3wRG/b8OjlZyGtS/ErCdasSZX4X9pcCklfFBonWGnRr9NwvPq2 Wb1WAB4qTVGgslaKu2r7ZzeIPuoOVwRbowkdmwmsa7fMhkhvXT0XcyQoS9baXsoXUv0ug0x+wMtj0 0xZdxa4cXawBKXyfOstdo/4e/bRsJzTTHzPTa8fRpq208vJ3+HMDozXgS0xczcukjijqYQ+bb3Oi9 xroZuogzwJTQw2LNUPWGqwFz7wvqwzx/AoSUPtWbWcBP2V7FeN5QQ0L+TBua+yj4ajDLd7t9tBsGd QUUfN2yQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBB9N-00000000cvP-1si3; Mon, 28 Sep 2026 13:12:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBB9L-00000000cux-1iAP; Mon, 28 Sep 2026 13:12:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 533E31655; Mon, 28 Sep 2026 06:12:00 -0700 (PDT) Received: from [10.0.153.43] (e121487-lin.cambridge.arm.com [10.0.153.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CE63B3F763; Mon, 28 Sep 2026 06:12:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790601123; bh=qARXK5luvst6TAFL4jAEw2OrBYm6ac8q5l9d2gaTyoI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=METk7VeL7FwsyTZ8S6FYEwMaMolu9SL5gg4JMZJsCAms92flWQLNTO0HCiIMZ6cfw qXRx0RjbLUZdADGQpCoYLhb8BCNpJ0xcQFrbQ/jqAgP2/WoFXV2uaPsd8MpcvdyxML mmDDNJ6/WsrqTFMR7q06quekokzYF9NS/iDNscJ0= Message-ID: <845ef1a3-8d85-4007-aa2c-05e59e79afcd@arm.com> Date: Mon, 28 Sep 2026 14:11:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] usb: mtu3: Fix double dereference in TP_printk To: linux-usb@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, chunfeng.yun@mediatek.com, gregkh@linuxfoundation.org, rostedt@goodmis.org, paulmck@kernel.org, mark.rutland@arm.com References: <20260922103756.104846-1-vladimir.murzin@arm.com> Content-Language: en-GB From: Vladimir Murzin In-Reply-To: <20260922103756.104846-1-vladimir.murzin@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260928_061207_551763_082CE744 X-CRM114-Status: GOOD ( 20.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi All, Gentle ping... spat is still present in v7.3-rc5 Cheers Vladimir On 9/22/26 11:37, Vladimir Murzin wrote: > Paul reported kernel splat: > > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma > [ 0.000000] ------------[ cut here ]------------ > [ 0.000000] Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma > [ 0.000000] WARNING: kernel/trace/trace_events.c:420 at test_double_dereference+0x144/0x14c, CPU#0: swapper/0/0 > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1 #15247 PREEMPT > [ 0.000000] Hardware name: linux,dummy-virt (DT) > [ 0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 0.000000] pc : test_double_dereference+0x144/0x14c > [ 0.000000] lr : test_double_dereference+0x144/0x14c > [ 0.000000] sp : ffffc80aa7633bf0 > [ 0.000000] x29: ffffc80aa7633bf0 x28: ffffc80aa7c0f047 x27: 000508b58019388f > [ 0.000000] x26: 0000000000000003 x25: 0000000000000007 x24: ffffc80aa5fceff8 > [ 0.000000] x23: ffffc80aa7c0f05a x22: ffffc80aa64edfe8 x21: ffffc80aa7c0fce8 > [ 0.000000] x20: ffffc80aa7c0f047 x19: 0000000000000013 x18: 0000000000000001 > [ 0.000000] x17: 6572656420656c62 x16: 756f642073616820 x15: 746c61685f746573 > [ 0.000000] x14: 0000000000000000 x13: ffff000139d90000 x12: 0000000000000045 > [ 0.000000] x11: 00000000000000cf x10: ffff00013f546428 x9 : ffff000139d90000 > [ 0.000000] x8 : 3fffffffffffc000 x7 : 0000000000000001 x6 : 0000000000000001 > [ 0.000000] x5 : ffff00013f4e6440 x4 : 0000000000000000 x3 : 0000000000000000 > [ 0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffc80aa764a700 > [ 0.000000] Call trace: > [ 0.000000] test_double_dereference+0x144/0x14c (P) > [ 0.000000] trace_event_raw_init+0x37c/0x5d8 > [ 0.000000] event_init+0x34/0xc0 > [ 0.000000] trace_event_init+0xec/0x588 > [ 0.000000] trace_init+0x24/0x6e0 > [ 0.000000] start_kernel+0x4a0/0x8ec > [ 0.000000] __primary_switched+0x88/0x90 > [ 0.000000] irq event stamp: 0 > [ 0.000000] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] hardirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] softirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.000000] ---[ end trace 0000000000000000 ]--- > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_disable has double dereference in TP_printk: &REC->gpd_ring->dma > [ 0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_enable has double dereference in TP_printk: &REC->gpd_ring->dma > > Which also observed by Mark and myself. > > The splat it result of new check introduced by b5cc230af5e5 ("tracing: > Warn when an event dereferences a pointer in TP_printk()") which > correctly catches issue with %pad dereferencing the address saved in > the ring buffer. TP_fast_assign() logic gets executed when the > tracepoint is triggered, however the TP_printk() is executed when the > user reads the trace buffer which could be seconds, minutes, hours, > days, even months later and nothing guarantee that __entry->gpd_ring > pointer will still be pointing to what it was when it was recorded. > > Fix the issue by capturing immediate value of gpd_ring.dma when trace > point is triggered. > > Reported-by: Paul E. McKenney > Tested-by: Mark Rutland > Reviewed-by: Steven Rostedt > Signed-off-by: Vladimir Murzin > --- > drivers/usb/mtu3/mtu3_trace.h | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/mtu3/mtu3_trace.h b/drivers/usb/mtu3/mtu3_trace.h > index 89870175d635..9aaa167d69c1 100644 > --- a/drivers/usb/mtu3/mtu3_trace.h > +++ b/drivers/usb/mtu3/mtu3_trace.h > @@ -224,6 +224,7 @@ DECLARE_EVENT_CLASS(mtu3_log_ep, > __field(unsigned int, flags) > __field(unsigned int, direction) > __field(struct mtu3_gpd_ring *, gpd_ring) > + __field(dma_addr_t, gpd_ring_dma) > ), > TP_fast_assign( > __assign_str(name); > @@ -235,12 +236,13 @@ DECLARE_EVENT_CLASS(mtu3_log_ep, > __entry->flags = mep->flags; > __entry->direction = mep->is_in; > __entry->gpd_ring = &mep->gpd_ring; > + __entry->gpd_ring_dma = mep->gpd_ring.dma > ), > TP_printk("%s: type %s maxp %d slot %d mult %d burst %d ring %p/%pad flags %c:%c%c%c:%c", > __get_str(name), usb_ep_type_string(__entry->type), > __entry->maxp, __entry->slot, > __entry->mult, __entry->maxburst, > - __entry->gpd_ring, &__entry->gpd_ring->dma, > + __entry->gpd_ring, &__entry->gpd_ring_dma, > __entry->flags & MTU3_EP_ENABLED ? 'E' : 'e', > __entry->flags & MTU3_EP_STALL ? 'S' : 's', > __entry->flags & MTU3_EP_WEDGE ? 'W' : 'w', > -- 2.34.1 >