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From:   Guenter Roeck <linux@roeck-us.net>
To:     Michael Ellerman <mpe@ellerman.id.au>
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Robin Murphy <robin.murphy@arm.com>,
        Christoph Hellwig <hch@lst.de>,
        Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH] powerpc/4xx: Fix error return path in ppc4xx_msi_probe()
Date:   Mon, 30 Jul 2018 18:44:14 -0700
Message-Id: <1533001454-8751-1-git-send-email-linux@roeck-us.net>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

An arbitrary error in ppc4xx_msi_probe() quite likely results in a
crash similar to the following, seen after dma_alloc_coherent()
returned an error.

Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc001bff0
Oops: Kernel access of bad area, sig: 11 [#1]
BE Canyonlands
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Tainted: G        W
4.18.0-rc6-00010-gff33d1030a6c #1
NIP:  c001bff0 LR: c001c418 CTR: c01faa7c
REGS: cf82db40 TRAP: 0300   Tainted: G        W
(4.18.0-rc6-00010-gff33d1030a6c)
MSR:  00029000 <CE,EE,ME>  CR: 28002024  XER: 00000000
DEAR: 00000000 ESR: 00000000
GPR00: c001c418 cf82dbf0 cf828000 cf8de400 00000000 00000000 000000c4 000000c4
GPR08: c0481ea4 00000000 00000000 000000c4 22002024 00000000 c00025e8 00000000
GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 c0492380 0000004a
GPR24: 00029000 0000000c 00000000 cf8de410 c0494d60 c0494d60 cf8bebc0 00000001
NIP [c001bff0] ppc4xx_of_msi_remove+0x48/0xa0
LR [c001c418] ppc4xx_msi_probe+0x294/0x3b8
Call Trace:
[cf82dbf0] [00029000] 0x29000 (unreliable)
[cf82dc10] [c001c418] ppc4xx_msi_probe+0x294/0x3b8
[cf82dc70] [c0209fbc] platform_drv_probe+0x40/0x9c
[cf82dc90] [c0208240] driver_probe_device+0x2a8/0x350
[cf82dcc0] [c0206204] bus_for_each_drv+0x60/0xac
[cf82dcf0] [c0207e88] __device_attach+0xe8/0x160
[cf82dd20] [c02071e0] bus_probe_device+0xa0/0xbc
[cf82dd40] [c02050c8] device_add+0x404/0x5c4
[cf82dd90] [c0288978] of_platform_device_create_pdata+0x88/0xd8
[cf82ddb0] [c0288b70] of_platform_bus_create+0x134/0x220
[cf82de10] [c0288bcc] of_platform_bus_create+0x190/0x220
[cf82de70] [c0288cf4] of_platform_bus_probe+0x98/0xec
[cf82de90] [c0449650] __machine_initcall_canyonlands_ppc460ex_device_probe+0x38/0x54
[cf82dea0] [c0002404] do_one_initcall+0x40/0x188
[cf82df00] [c043daec] kernel_init_freeable+0x130/0x1d0
[cf82df30] [c0002600] kernel_init+0x18/0x104
[cf82df40] [c000c23c] ret_from_kernel_thread+0x14/0x1c
Instruction dump:
90010024 813d0024 2f890000 83c30058 41bd0014 48000038 813d0024 7f89f800
409d002c 813e000c 57ea103a 3bff0001 <7c69502e> 2f830000 419effe0 4803b26d
---[ end trace 8cf551077ecfc42a ]---

Fix it up. Specifically,

- Return valid error codes from ppc4xx_setup_pcieh_hw(), have it clean
  up after itself, and only access hardware after all possible error
  conditions have been handled.
- Use devm_kzalloc() instead of kzalloc() in ppc4xx_msi_probe()

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 arch/powerpc/platforms/4xx/msi.c | 51 +++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/platforms/4xx/msi.c b/arch/powerpc/platforms/4xx/msi.c
index 81b2cbce7df8..7c324eff2f22 100644
--- a/arch/powerpc/platforms/4xx/msi.c
+++ b/arch/powerpc/platforms/4xx/msi.c
@@ -146,13 +146,19 @@ static int ppc4xx_setup_pcieh_hw(struct platform_device *dev,
 	const u32 *sdr_addr;
 	dma_addr_t msi_phys;
 	void *msi_virt;
+	int err;
 
 	sdr_addr = of_get_property(dev->dev.of_node, "sdr-base", NULL);
 	if (!sdr_addr)
-		return -1;
+		return -EINVAL;
 
-	mtdcri(SDR0, *sdr_addr, upper_32_bits(res.start));	/*HIGH addr */
-	mtdcri(SDR0, *sdr_addr + 1, lower_32_bits(res.start));	/* Low addr */
+	msi_data = of_get_property(dev->dev.of_node, "msi-data", NULL);
+	if (!msi_data)
+		return -EINVAL;
+
+	msi_mask = of_get_property(dev->dev.of_node, "msi-mask", NULL);
+	if (!msi_mask)
+		return -EINVAL;
 
 	msi->msi_dev = of_find_node_by_name(NULL, "ppc4xx-msi");
 	if (!msi->msi_dev)
@@ -160,30 +166,30 @@ static int ppc4xx_setup_pcieh_hw(struct platform_device *dev,
 
 	msi->msi_regs = of_iomap(msi->msi_dev, 0);
 	if (!msi->msi_regs) {
-		dev_err(&dev->dev, "of_iomap problem failed\n");
-		return -ENOMEM;
+		dev_err(&dev->dev, "of_iomap failed\n");
+		err = -ENOMEM;
+		goto node_put;
 	}
 	dev_dbg(&dev->dev, "PCIE-MSI: msi register mapped 0x%x 0x%x\n",
 		(u32) (msi->msi_regs + PEIH_TERMADH), (u32) (msi->msi_regs));
 
 	msi_virt = dma_alloc_coherent(&dev->dev, 64, &msi_phys, GFP_KERNEL);
-	if (!msi_virt)
-		return -ENOMEM;
+	if (!msi_virt) {
+		err = -ENOMEM;
+		goto iounmap;
+	}
 	msi->msi_addr_hi = upper_32_bits(msi_phys);
 	msi->msi_addr_lo = lower_32_bits(msi_phys & 0xffffffff);
 	dev_dbg(&dev->dev, "PCIE-MSI: msi address high 0x%x, low 0x%x\n",
 		msi->msi_addr_hi, msi->msi_addr_lo);
 
+	mtdcri(SDR0, *sdr_addr, upper_32_bits(res.start));	/*HIGH addr */
+	mtdcri(SDR0, *sdr_addr + 1, lower_32_bits(res.start));	/* Low addr */
+
 	/* Progam the Interrupt handler Termination addr registers */
 	out_be32(msi->msi_regs + PEIH_TERMADH, msi->msi_addr_hi);
 	out_be32(msi->msi_regs + PEIH_TERMADL, msi->msi_addr_lo);
 
-	msi_data = of_get_property(dev->dev.of_node, "msi-data", NULL);
-	if (!msi_data)
-		return -1;
-	msi_mask = of_get_property(dev->dev.of_node, "msi-mask", NULL);
-	if (!msi_mask)
-		return -1;
 	/* Program MSI Expected data and Mask bits */
 	out_be32(msi->msi_regs + PEIH_MSIED, *msi_data);
 	out_be32(msi->msi_regs + PEIH_MSIMK, *msi_mask);
@@ -191,6 +197,12 @@ static int ppc4xx_setup_pcieh_hw(struct platform_device *dev,
 	dma_free_coherent(&dev->dev, 64, msi_virt, msi_phys);
 
 	return 0;
+
+iounmap:
+	iounmap(msi->msi_regs);
+node_put:
+	of_node_put(msi->msi_dev);
+	return err;
 }
 
 static int ppc4xx_of_msi_remove(struct platform_device *dev)
@@ -209,7 +221,6 @@ static int ppc4xx_of_msi_remove(struct platform_device *dev)
 		msi_bitmap_free(&msi->bitmap);
 	iounmap(msi->msi_regs);
 	of_node_put(msi->msi_dev);
-	kfree(msi);
 
 	return 0;
 }
@@ -223,18 +234,16 @@ static int ppc4xx_msi_probe(struct platform_device *dev)
 
 	dev_dbg(&dev->dev, "PCIE-MSI: Setting up MSI support...\n");
 
-	msi = kzalloc(sizeof(*msi), GFP_KERNEL);
-	if (!msi) {
-		dev_err(&dev->dev, "No memory for MSI structure\n");
+	msi = devm_kzalloc(&dev->dev, sizeof(*msi), GFP_KERNEL);
+	if (!msi)
 		return -ENOMEM;
-	}
 	dev->dev.platform_data = msi;
 
 	/* Get MSI ranges */
 	err = of_address_to_resource(dev->dev.of_node, 0, &res);
 	if (err) {
 		dev_err(&dev->dev, "%pOF resource error!\n", dev->dev.of_node);
-		goto error_out;
+		return err;
 	}
 
 	msi_irqs = of_irq_count(dev->dev.of_node);
@@ -243,7 +252,7 @@ static int ppc4xx_msi_probe(struct platform_device *dev)
 
 	err = ppc4xx_setup_pcieh_hw(dev, res, msi);
 	if (err)
-		goto error_out;
+		return err;
 
 	err = ppc4xx_msi_init_allocator(dev, msi);
 	if (err) {
@@ -256,7 +265,7 @@ static int ppc4xx_msi_probe(struct platform_device *dev)
 		phb->controller_ops.setup_msi_irqs = ppc4xx_setup_msi_irqs;
 		phb->controller_ops.teardown_msi_irqs = ppc4xx_teardown_msi_irqs;
 	}
-	return err;
+	return 0;
 
 error_out:
 	ppc4xx_of_msi_remove(dev);
-- 
2.7.4