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 2225FC982F1 for ; Tue, 22 Sep 2026 10:38:46 +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: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=npxqYAoA7IwkUE88Ybw2nQQ/5lB1zYdS7If1dwmwfYs=; b=KP6+hwopIgwKA20z7E0pd+MUzI F72qrPaiKxe2q9fCRs/Tshaw2d0mPHo5ln9zaowzdtuoO7kmNt2cw8vOC8XuqibZgfLAPW7AAT3ga HsroB1GKQnwQjoDM6eMv/h1GYl9jeh3G6EmT+lGalGvSxpnSMcKzR0wkQmsWtn5ZqrOYIG7cOBgYW KfuBcyaSwH+qaQldbtvaJ6XO26LitJin0aRYK9lJR76QcQNOWh15pKiQWTX3fvre1cm09pdQboIVw UOUNgNSIA7gCZE6eBa7x7OjSf2R3IgrMVevrwfSSSmLZ212ABRMJav/k5CvUK9t58/Gedrun88uRL 40UH3czg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8xtd-000000054or-0qa8; Tue, 22 Sep 2026 10:38:45 +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 1x8xta-000000054nj-49Yj; Tue, 22 Sep 2026 10:38:44 +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 14ACD1576; Tue, 22 Sep 2026 03:38:38 -0700 (PDT) Received: from login2.euhpc2.arm.com (login2.euhpc2.arm.com [10.58.100.22]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 3ABA73F632; Tue, 22 Sep 2026 03:38:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790073521; bh=0EIXjeyAI4S9Q4d29IPfXdLZ0TzlUX09hLhqO14gjnM=; h=From:To:Cc:Subject:Date:From; b=vIZAJbEWTlXPu/VZ4y7Cm3s/P8h40IGvctRJFvrzCHJ5H+8HiL2pAfQt88fs1Solb aUxNZE4rOt04rTDkEvhb2lyVfRs71xEZ3VtVdQlZGvJN/mMMyvAA86bEcXA47TNypW Gm9aNnZh0od7w05bLPzZMzlzG8GTKGWc4tZ1Ctjs= From: Vladimir Murzin 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, Vladimir Murzin Subject: [PATCH] usb: mtu3: Fix double dereference in TP_printk Date: Tue, 22 Sep 2026 11:37:56 +0100 Message-Id: <20260922103756.104846-1-vladimir.murzin@arm.com> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260922_033843_147595_61B022B0 X-CRM114-Status: GOOD ( 12.67 ) X-BeenThere: linux-mediatek@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-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org 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