linux-kernel - [PATCH v2] ath11k: mhi: fix potential memory leak in ath11k_mhi

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Date:   Mon, 30 May 2022 16:06:10 +0800
From:   Jianglei Nie <niejianglei2021@....com>
To:     kvalo@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com
Cc:     ath11k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jianglei Nie <niejianglei2021@....com>
Subject: [PATCH v2] ath11k: mhi: fix potential memory leak in ath11k_mhi_register()

mhi_alloc_controller() allocates a memory space for mhi_ctrl. When some
errors occur, mhi_ctrl should be freed by mhi_free_controller() and set
ab_pci->mhi_ctrl = NULL because ab_pci->mhi_ctrl has a dangling pointer
to the freed memory. But when ath11k_mhi_read_addr_from_dt() fails, the
function returns without calling mhi_free_controller(), which will lead
to a memory leak.

We can fix it by calling mhi_free_controller() when
ath11k_mhi_read_addr_from_dt() fails and set ab_pci->mhi_ctrl = NULL in
all of the places where we call mhi_free_controller().

Signed-off-by: Jianglei Nie <niejianglei2021@....com>
---
 drivers/net/wireless/ath/ath11k/mhi.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mhi.c b/drivers/net/wireless/ath/ath11k/mhi.c
index fc3524e83e52..fc1bbf91c58e 100644
--- a/drivers/net/wireless/ath/ath11k/mhi.c
+++ b/drivers/net/wireless/ath/ath11k/mhi.c
@@ -367,8 +367,7 @@ int ath11k_mhi_register(struct ath11k_pci *ab_pci)
 	ret = ath11k_mhi_get_msi(ab_pci);
 	if (ret) {
 		ath11k_err(ab, "failed to get msi for mhi\n");
-		mhi_free_controller(mhi_ctrl);
-		return ret;
+		goto free_controller;
 	}
 
 	if (!test_bit(ATH11K_PCI_FLAG_MULTI_MSI_VECTORS, &ab_pci->flags))
@@ -377,7 +376,7 @@ int ath11k_mhi_register(struct ath11k_pci *ab_pci)
 	if (test_bit(ATH11K_FLAG_FIXED_MEM_RGN, &ab->dev_flags)) {
 		ret = ath11k_mhi_read_addr_from_dt(mhi_ctrl);
 		if (ret < 0)
-			return ret;
+			goto free_controller;
 	} else {
 		mhi_ctrl->iova_start = 0;
 		mhi_ctrl->iova_stop = 0xFFFFFFFF;
@@ -405,18 +404,22 @@ int ath11k_mhi_register(struct ath11k_pci *ab_pci)
 	default:
 		ath11k_err(ab, "failed assign mhi_config for unknown hw rev %d\n",
 			   ab->hw_rev);
-		mhi_free_controller(mhi_ctrl);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto free_controller;
 	}
 
 	ret = mhi_register_controller(mhi_ctrl, ath11k_mhi_config);
 	if (ret) {
 		ath11k_err(ab, "failed to register to mhi bus, err = %d\n", ret);
-		mhi_free_controller(mhi_ctrl);
-		return ret;
+		goto free_controller;
 	}
 
 	return 0;
+
+free_controller:
+	mhi_free_controller(mhi_ctrl);
+	ab_pci->mhi_ctrl = NULL;
+	return ret;
 }
 
 void ath11k_mhi_unregister(struct ath11k_pci *ab_pci)
-- 
2.25.1