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From:   Marek Szyprowski <m.szyprowski@samsung.com>
To:     linux-samsung-soc@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [PATCH] phy: core: Fix error path in devm_of_phy_get()
Date:   Wed,  8 Jan 2020 14:23:42 +0100
Message-Id: <20200108132342.14635-1-m.szyprowski@samsung.com>
Content-Type: text/plain; charset="utf-8"
CMS-TYPE: 201P
References: <CGME20200108132350eucas1p1476f4aa038dbf5ea199b84c5c82a25a5@eucas1p1.samsung.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Commit 5253fe05bb47 ("phy: core: Add consumer device link support") added
support for consumer device links, but it missed proper update for error
handling in devm_of_phy_get(). Fix this by adding proper return statement.

This patch fixes the following invalid pointer dereference on
Exynos5250-based Arndale board with multi_v7_defconfig:

8<--- cut here ---
Unable to handle kernel paging request at virtual address fffffe7f
pgd = (ptrval)
[fffffe7f] *pgd=6ffff841, *pte=00000000, *ppte=00000000
Internal error: Oops: 27 [#1] SMP ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc5-next-20200108 #167
Hardware name: Samsung Exynos (Flattened Device Tree)
PC is at device_link_add+0x68/0x4c4
LR is at device_link_add+0x68/0x4c4
...
Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
...
[<c0984d70>] (device_link_add) from [<c0707e8c>] (devm_of_phy_get+0x6c/0xb0)
[<c0707e8c>] (devm_of_phy_get) from [<c0a0deb8>] (ahci_platform_get_phy+0x28/0xe0)
[<c0a0deb8>] (ahci_platform_get_phy) from [<c0a0e64c>] (ahci_platform_get_resources+0x398/0x48c)
[<c0a0e64c>] (ahci_platform_get_resources) from [<c0a0daec>] (ahci_probe+0x14/0xb4)
[<c0a0daec>] (ahci_probe) from [<c098a1ec>] (platform_drv_probe+0x48/0x9c)
[<c098a1ec>] (platform_drv_probe) from [<c0988214>] (really_probe+0x1dc/0x33c)
[<c0988214>] (really_probe) from [<c09884f4>] (driver_probe_device+0x60/0x164)
[<c09884f4>] (driver_probe_device) from [<c09887a0>] (device_driver_attach+0x58/0x60)
[<c09887a0>] (device_driver_attach) from [<c0988828>] (__driver_attach+0x80/0xbc)
[<c0988828>] (__driver_attach) from [<c09865b4>] (bus_for_each_dev+0x68/0xb4)
[<c09865b4>] (bus_for_each_dev) from [<c0987594>] (bus_add_driver+0x160/0x1e4)
[<c0987594>] (bus_add_driver) from [<c09892c0>] (driver_register+0x78/0x10c)
[<c09892c0>] (driver_register) from [<c0302f14>] (do_one_initcall+0x54/0x220)
[<c0302f14>] (do_one_initcall) from [<c1500f4c>] (kernel_init_freeable+0x150/0x1b4)
[<c1500f4c>] (kernel_init_freeable) from [<c0ef6b34>] (kernel_init+0x8/0x10c)
[<c0ef6b34>] (kernel_init) from [<c03010e8>] (ret_from_fork+0x14/0x2c)
...

Fixes: 5253fe05bb47 ("phy: core: Add consumer device link support")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 drivers/phy/phy-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index 8dfb4868c8c3..2eb28cc2d2dc 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -799,6 +799,7 @@ struct phy *devm_of_phy_get(struct device *dev, struct device_node *np,
 		devres_add(dev, ptr);
 	} else {
 		devres_free(ptr);
+		return phy;
 	}
 
 	link = device_link_add(dev, &phy->dev, DL_FLAG_STATELESS);
-- 
2.17.1