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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Takashi Iwai <tiwai@suse.de>,
        Yu Zhao <yuzhao@google.com>, Mark Brown <broonie@kernel.org>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 05/48] sound: enable interrupt after dma buffer initialization
Date:   Thu, 18 Oct 2018 19:54:40 +0200
Message-Id: <20181018175428.156233663@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yu Zhao <yuzhao@google.com>

[ Upstream commit b61749a89f826eb61fc59794d9e4697bd246eb61 ]

In snd_hdac_bus_init_chip(), we enable interrupt before
snd_hdac_bus_init_cmd_io() initializing dma buffers. If irq has
been acquired and irq handler uses the dma buffer, kernel may crash
when interrupt comes in.

Fix the problem by postponing enabling irq after dma buffer
initialization. And warn once on null dma buffer pointer during the
initialization.

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/hda/hdac_controller.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/sound/hda/hdac_controller.c
+++ b/sound/hda/hdac_controller.c
@@ -40,6 +40,8 @@ static void azx_clear_corbrp(struct hdac
  */
 void snd_hdac_bus_init_cmd_io(struct hdac_bus *bus)
 {
+	WARN_ON_ONCE(!bus->rb.area);
+
 	spin_lock_irq(&bus->reg_lock);
 	/* CORB set up */
 	bus->corb.addr = bus->rb.addr;
@@ -377,13 +379,15 @@ bool snd_hdac_bus_init_chip(struct hdac_
 	/* reset controller */
 	azx_reset(bus, full_reset);
 
-	/* initialize interrupts */
+	/* clear interrupts */
 	azx_int_clear(bus);
-	azx_int_enable(bus);
 
 	/* initialize the codec command I/O */
 	snd_hdac_bus_init_cmd_io(bus);
 
+	/* enable interrupts after CORB/RIRB buffers are initialized above */
+	azx_int_enable(bus);
+
 	/* program the position buffer */
 	if (bus->use_posbuf && bus->posbuf.addr) {
 		snd_hdac_chip_writel(bus, DPLBASE, (u32)bus->posbuf.addr);