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mmc: cqhci: Fix a tiny potential memory leak on error condition

PATCH In review Alamy Liu 2 participants 3 messages Jan 16, 2019 – Jan 31, 2019

Subsystems (2)
MMC, SD and SDIO eMMC CMDQ host controller interface (CQHCI) driver
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Alamy Liu

author
#0 lore raw

PATCH 1/1 mmc: cqhci: Fix a tiny potential memory leak on error condition

In the error case:
either cq_host->desc_base

       or cq_host->trans_desc_base

might have been granted memory successfully.

The value of mmc_host->cqe_enabled stays 'false'.
Thus, cqhci_disable (mmc_cqe_ops->cqe_disable) won't be called to free the memory.
Also, cqhci_disable() is designed to disable and free all resources, not suitable to handle this corner case.

Signed-off-by Alamy Liu <[email protected]>
---
 drivers/mmc/host/cqhci.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)
drivers/mmc/host/cqhci.c +19 -1
index 974997b6cb..58ad8cd613 100644
@@ -223,7 +223,7 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 					      &cq_host->trans_desc_dma_base,
 					      GFP_KERNEL);
 	if (!cq_host->desc_base || !cq_host->trans_desc_base)
-		return -ENOMEM;
+		goto err_free_dma;
 
 	pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
 		 mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,

@@ -234,6 +234,24 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 		setup_trans_desc(cq_host, i);
 
 	return 0;
+
+err_free_dma:
+	if (cq_host->desc_base) {
+		dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
+				   cq_host->desc_base,
+				   cq_host->desc_dma_base);
+		cq_host->desc_base = NULL;
+		cq_host->desc_dma_base = 0;
+	}
+	if (cq_host->trans_desc_base) {
+		dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->data_size,
+				   cq_host->trans_desc_base,
+				   cq_host->trans_desc_dma_base);
+		cq_host->trans_desc_base = NULL;
+		cq_host->trans_desc_dma_base = 0;
+	}
+
+	return -ENOMEM;
 }
 
 static void __cqhci_enable(struct cqhci_host *cq_host)
Signature · 1 line
2.17.1
maintainer
#1 lore raw
Quoted 45 lines · Alamy Liu

In the error case:

   either cq_host->desc_base
       or cq_host->trans_desc_base

might have been granted memory successfully.

The value of mmc_host->cqe_enabled stays 'false'.
Thus, cqhci_disable (mmc_cqe_ops->cqe_disable) won't be called to free the memory.
Also, cqhci_disable() is designed to disable and free all resources, not suitable to handle this corner case.

Signed-off-by Alamy Liu <[email protected]>
---
 drivers/mmc/host/cqhci.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)
drivers/mmc/host/cqhci.c +12 -1
index 974997b6cb..58ad8cd613 100644
@@ -223,7 +223,7 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 					      &cq_host->trans_desc_dma_base,
 					      GFP_KERNEL);
 	if (!cq_host->desc_base || !cq_host->trans_desc_base)
-		return -ENOMEM;
+		goto err_free_dma;
 
 	pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
 		 mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,

@@ -234,6 +234,24 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 		setup_trans_desc(cq_host, i);
 
 	return 0;
+
+err_free_dma:
+	if (cq_host->desc_base) {
+		dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
+				   cq_host->desc_base,
+				   cq_host->desc_dma_base);
+		cq_host->desc_base = NULL;
+		cq_host->desc_dma_base = 0;
+	}
+	if (cq_host->trans_desc_base) {
+		dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->data_size,

drivers/mmc/host/cqhci.c static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host) · line 257

Quoted 10 lines
drivers/mmc/host/cqhci.c +7 -0
+				   cq_host->trans_desc_base,
+				   cq_host->trans_desc_dma_base);
+		cq_host->trans_desc_base = NULL;
+		cq_host->trans_desc_dma_base = 0;
+	}
+
+	return -ENOMEM;
 }
 
 static void __cqhci_enable(struct cqhci_host *cq_host)

Normally, error handling is done step-by-step e.g.

drivers/mmc/host/cqhci.c +12 -2
index 26d63594b7ea..d015b465ade4 100644
@@ -217,12 +217,15 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 						 cq_host->desc_size,
 						 &cq_host->desc_dma_base,
 						 GFP_KERNEL);
+	if (!cq_host->desc_base)
+		return -ENOMEM;
+
 	cq_host->trans_desc_base = dmam_alloc_coherent(mmc_dev(cq_host->mmc),
 					      cq_host->data_size,
 					      &cq_host->trans_desc_dma_base,
 					      GFP_KERNEL);
-	if (!cq_host->desc_base || !cq_host->trans_desc_base)
-		return -ENOMEM;
+	if (!cq_host->trans_desc_base)
+		goto err_free_dma;
 
 	pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
 		 mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,

@@ -233,6 +236,13 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 		setup_trans_desc(cq_host, i);
 
 	return 0;
+
+err_free_dma:
+	dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
+			   cq_host->desc_base, cq_host->desc_dma_base);
+	cq_host->desc_base = NULL;
+	cq_host->desc_dma_base = 0;
+	return NULL;
 }
 
 static void __cqhci_enable(struct cqhci_host *cq_host)
maintainer
#2 lore raw
Quoted 82 lines · Adrian Hunter
Quoted 45 lines · Alamy Liu

In the error case:

   either cq_host->desc_base
       or cq_host->trans_desc_base

might have been granted memory successfully.

The value of mmc_host->cqe_enabled stays 'false'.
Thus, cqhci_disable (mmc_cqe_ops->cqe_disable) won't be called to free the memory.
Also, cqhci_disable() is designed to disable and free all resources, not suitable to handle this corner case.

Signed-off-by Alamy Liu <[email protected]>
---
 drivers/mmc/host/cqhci.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)
drivers/mmc/host/cqhci.c +12 -1
index 974997b6cb..58ad8cd613 100644
@@ -223,7 +223,7 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 					      &cq_host->trans_desc_dma_base,
 					      GFP_KERNEL);
 	if (!cq_host->desc_base || !cq_host->trans_desc_base)
-		return -ENOMEM;
+		goto err_free_dma;
 
 	pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
 		 mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,

@@ -234,6 +234,24 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 		setup_trans_desc(cq_host, i);
 
 	return 0;
+
+err_free_dma:
+	if (cq_host->desc_base) {
+		dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
+				   cq_host->desc_base,
+				   cq_host->desc_dma_base);
+		cq_host->desc_base = NULL;
+		cq_host->desc_dma_base = 0;
+	}
+	if (cq_host->trans_desc_base) {
+		dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->data_size,

drivers/mmc/host/cqhci.c static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host) · line 257

Quoted 10 lines
drivers/mmc/host/cqhci.c +7 -0
+				   cq_host->trans_desc_base,
+				   cq_host->trans_desc_dma_base);
+		cq_host->trans_desc_base = NULL;
+		cq_host->trans_desc_dma_base = 0;
+	}
+
+	return -ENOMEM;
 }
 
 static void __cqhci_enable(struct cqhci_host *cq_host)

Normally, error handling is done step-by-step e.g.

drivers/mmc/host/cqhci.c +5 -2
index 26d63594b7ea..d015b465ade4 100644
@@ -217,12 +217,15 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 						 cq_host->desc_size,
 						 &cq_host->desc_dma_base,
 						 GFP_KERNEL);
+	if (!cq_host->desc_base)
+		return -ENOMEM;
+
 	cq_host->trans_desc_base = dmam_alloc_coherent(mmc_dev(cq_host->mmc),
 					      cq_host->data_size,
 					      &cq_host->trans_desc_dma_base,
 					      GFP_KERNEL);
-	if (!cq_host->desc_base || !cq_host->trans_desc_base)
-		return -ENOMEM;
+	if (!cq_host->trans_desc_base)
+		goto err_free_dma;
 
 	pr_debug("%s: cqhci: desc-base: 0x%p trans-base: 0x%p\n desc_dma 0x%llx trans_dma: 0x%llx\n",
 		 mmc_hostname(cq_host->mmc), cq_host->desc_base, cq_host->trans_desc_base,

drivers/mmc/host/cqhci.c static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host) · line 245

Quoted 10 lines
drivers/mmc/host/cqhci.c +7 -0
@@ -233,6 +236,13 @@ static int cqhci_host_alloc_tdl(struct cqhci_host *cq_host)
 		setup_trans_desc(cq_host, i);
 
 	return 0;
+
+err_free_dma:
+	dmam_free_coherent(mmc_dev(cq_host->mmc), cq_host->desc_size,
+			   cq_host->desc_base, cq_host->desc_dma_base);
+	cq_host->desc_base = NULL;
+	cq_host->desc_dma_base = 0;
+	return NULL;

That should be

	return -ENOMEM;
Quoted 4 lines
drivers/mmc/host/cqhci.c +0 -0
 }
 
 static void __cqhci_enable(struct cqhci_host *cq_host)