linux-kernel - [PATCH v3] firmware_loader: fix memory leak for paged buffer

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Message-Id: <1597957070-27185-1-git-send-email-prsood@codeaurora.org>
Date:   Fri, 21 Aug 2020 02:27:50 +0530
From:   Prateek Sood <prsood@...eaurora.org>
To:     tiwai@...e.de, mcgrof@...nel.org, gregkh@...uxfoundation.org,
        rafael@...nel.org
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Prateek Sood <prsood@...eaurora.org>
Subject: [PATCH v3] firmware_loader: fix memory leak for paged buffer

vfree() is being called on paged buffer allocated
using alloc_page() and mapped using vmap().

Freeing of pages in vfree() relies on nr_pages of
struct vm_struct. vmap() does not update nr_pages.
It can lead to memory leaks.

Fixes: ddaf29fd9bb6 ("firmware: Free temporary page table after vmapping")
Signed-off-by: Prateek Sood <prsood@...eaurora.org>
Reviewed-by: Takashi Iwai <tiwai@...e.de>
Cc: stable@...r.kernel.org
---
 drivers/base/firmware_loader/firmware.h |  2 ++
 drivers/base/firmware_loader/main.c     | 17 +++++++++++------
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
index 933e2192..d08efc7 100644
--- a/drivers/base/firmware_loader/firmware.h
+++ b/drivers/base/firmware_loader/firmware.h
@@ -142,10 +142,12 @@ static inline void fw_state_done(struct fw_priv *fw_priv)
 void fw_free_paged_buf(struct fw_priv *fw_priv);
 int fw_grow_paged_buf(struct fw_priv *fw_priv, int pages_needed);
 int fw_map_paged_buf(struct fw_priv *fw_priv);
+bool fw_is_paged_buf(struct fw_priv *fw_priv);
 #else
 static inline void fw_free_paged_buf(struct fw_priv *fw_priv) {}
 static inline int fw_grow_paged_buf(struct fw_priv *fw_priv, int pages_needed) { return -ENXIO; }
 static inline int fw_map_paged_buf(struct fw_priv *fw_priv) { return -ENXIO; }
+static inline bool fw_is_paged_buf(struct fw_priv *fw_priv) { return false; }
 #endif
 
 #endif /* __FIRMWARE_LOADER_H */
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index ca871b1..36bf455 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -252,9 +252,11 @@ static void __free_fw_priv(struct kref *ref)
 	list_del(&fw_priv->list);
 	spin_unlock(&fwc->lock);
 
-	fw_free_paged_buf(fw_priv); /* free leftover pages */
-	if (!fw_priv->allocated_size)
+	if (fw_is_paged_buf(fw_priv))
+		fw_free_paged_buf(fw_priv);
+	else if (!fw_priv->allocated_size)
 		vfree(fw_priv->data);
+
 	kfree_const(fw_priv->fw_name);
 	kfree(fw_priv);
 }
@@ -268,6 +270,11 @@ static void free_fw_priv(struct fw_priv *fw_priv)
 }
 
 #ifdef CONFIG_FW_LOADER_PAGED_BUF
+bool fw_is_paged_buf(struct fw_priv *fw_priv)
+{
+	return fw_priv->is_paged_buf;
+}
+
 void fw_free_paged_buf(struct fw_priv *fw_priv)
 {
 	int i;
@@ -275,6 +282,8 @@ void fw_free_paged_buf(struct fw_priv *fw_priv)
 	if (!fw_priv->pages)
 		return;
 
+	vunmap(fw_priv->data);
+
 	for (i = 0; i < fw_priv->nr_pages; i++)
 		__free_page(fw_priv->pages[i]);
 	kvfree(fw_priv->pages);
@@ -328,10 +337,6 @@ int fw_map_paged_buf(struct fw_priv *fw_priv)
 	if (!fw_priv->data)
 		return -ENOMEM;
 
-	/* page table is no longer needed after mapping, let's free */
-	kvfree(fw_priv->pages);
-	fw_priv->pages = NULL;
-
 	return 0;
 }
 #endif
-- 
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