[PATCH] phy: core: Fix error path in devm_of_phy_get()

[PATCH] phy: core: Fix error path in devm_of_phy_get()

[Marek Szyprowski]

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

Re: [PATCH] phy: core: Fix error path in devm_of_phy_get()

[Kishon Vijay Abraham I]

On 08/01/20 6:53 PM, Marek Szyprowski wrote:
> 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)

I've already merged a patch fixing this.

Thanks
Kishon

> ...
> 
> 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);
>