linux-kernel - [PATCH] ata: ahci_platform: fix null-ptr-deref in ahci_platform_enable

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Message-ID: <20211013061631.2958938-1-wanghai38@huawei.com>
Date:   Wed, 13 Oct 2021 14:16:31 +0800
From:   Wang Hai <wanghai38@...wei.com>
To:     <hdegoede@...hat.com>, <axboe@...nel.dk>,
        <damien.lemoal@...nsource.wdc.com>, <lgirdwood@...il.com>,
        <broonie@...nel.org>
CC:     <linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] ata: ahci_platform: fix null-ptr-deref in ahci_platform_enable_regulators()

I got a null-ptr-deref report:

KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
...
RIP: 0010:regulator_enable+0x84/0x260
...
Call Trace:
 ahci_platform_enable_regulators+0xae/0x320
 ahci_platform_enable_resources+0x1a/0x120
 ahci_probe+0x4f/0x1b9
 platform_probe+0x10b/0x280
...
 entry_SYSCALL_64_after_hwframe+0x44/0xae

If devm_regulator_get() in ahci_platform_get_resources() fails,
hpriv->phy_regulator will point to NULL, when enabling or disabling it,
null-ptr-deref will occur.

ahci_probe()
	ahci_platform_get_resources()
		devm_regulator_get(, "phy") // failed, let phy_regulator = NULL
	ahci_platform_enable_resources()
		ahci_platform_enable_regulators()
			regulator_enable(hpriv->phy_regulator) // null-ptr-deref

commit 962399bb7fbf ("ata: libahci_platform: Fix regulator_get_optional()
misuse") replaces devm_regulator_get_optional() with devm_regulator_get(),
but PHY regulator omits to delete "hpriv->phy_regulator = NULL;" like AHCI.
Delete it like AHCI regulator to fix this bug.

Fixes: commit 962399bb7fbf ("ata: libahci_platform: Fix regulator_get_optional() misuse")
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Wang Hai <wanghai38@...wei.com>
---
 drivers/ata/libahci_platform.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
index b2f552088291..0910441321f7 100644
--- a/drivers/ata/libahci_platform.c
+++ b/drivers/ata/libahci_platform.c
@@ -440,10 +440,7 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
 	hpriv->phy_regulator = devm_regulator_get(dev, "phy");
 	if (IS_ERR(hpriv->phy_regulator)) {
 		rc = PTR_ERR(hpriv->phy_regulator);
-		if (rc == -EPROBE_DEFER)
-			goto err_out;
-		rc = 0;
-		hpriv->phy_regulator = NULL;
+		goto err_out;
 	}

 	if (flags & AHCI_PLATFORM_GET_RESETS) {
-- 
2.17.1