f2fs: avoid overflow when large directory feathure is enabled

PATCH Superseded Chao Yu 2 participants 3 messages May 27, 2014

Subsystems (2)

VFS F2FS file system

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Chao Yu

author

2014-05-27 01:06 UTC #0 lore raw

PATCH 1/1 f2fs: avoid overflow when large directory feathure is enabled

When large directory feathure is enable, We have one case which could cause overflow in dir_buckets() as following:
special case: level + dir_level >= 32 and level < MAX_DIR_HASH_DEPTH / 2.

Here we define MAX_DIR_BUCKETS to limit the return value when the condition could trigger potential overflow.

Signed-off-by Chao Yu <[email protected]>

---
 fs/f2fs/dir.c           |    4 ++--
 include/linux/f2fs_fs.h |    3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

fs/f2fs/dir.c +2 -2

index c3f1485..966acb0 100644
@@ -23,10 +23,10 @@ static unsigned long dir_blocks(struct inode *inode)
 
 static unsigned int dir_buckets(unsigned int level, int dir_level)
 {
-	if (level < MAX_DIR_HASH_DEPTH / 2)
+	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
 		return 1 << (level + dir_level);
 	else
-		return 1 << ((MAX_DIR_HASH_DEPTH / 2 + dir_level) - 1);
+		return MAX_DIR_BUCKETS;
 }
 
 static unsigned int bucket_blocks(unsigned int level)

include/linux/f2fs_fs.h +3 -0

index 8c03f71..ba6f312 100644
@@ -394,6 +394,9 @@ typedef __le32	f2fs_hash_t;
 /* MAX level for dir lookup */
 #define MAX_DIR_HASH_DEPTH	63
 
+/* MAX buckets in one level of dir */
+#define MAX_DIR_BUCKETS		(1 << ((MAX_DIR_HASH_DEPTH / 2) - 1))
+
 #define SIZE_OF_DIR_ENTRY	11	/* by byte */
 #define SIZE_OF_DENTRY_BITMAP	((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
 					BITS_PER_BYTE)

Signature · 10 lines

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Changman Lee

2014-05-27 06:23 UTC #1 lore raw

Hi, Chao
Good catch. Please, modify Documentation/filesytems/f2fs.txt

Quoted 59 lines · Chao Yu

When large directory feathure is enable, We have one case which could cause overflow in dir_buckets() as following:
special case: level + dir_level >= 32 and level < MAX_DIR_HASH_DEPTH / 2.

Here we define MAX_DIR_BUCKETS to limit the return value when the condition could trigger potential overflow.

Signed-off-by Chao Yu <[email protected]>

---
 fs/f2fs/dir.c           |    4 ++--
 include/linux/f2fs_fs.h |    3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

fs/f2fs/dir.c +2 -2

index c3f1485..966acb0 100644
@@ -23,10 +23,10 @@ static unsigned long dir_blocks(struct inode *inode)
 
 static unsigned int dir_buckets(unsigned int level, int dir_level)
 {
-	if (level < MAX_DIR_HASH_DEPTH / 2)
+	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
 		return 1 << (level + dir_level);
 	else
-		return 1 << ((MAX_DIR_HASH_DEPTH / 2 + dir_level) - 1);
+		return MAX_DIR_BUCKETS;
 }
 
 static unsigned int bucket_blocks(unsigned int level)

include/linux/f2fs_fs.h +3 -0

index 8c03f71..ba6f312 100644
@@ -394,6 +394,9 @@ typedef __le32	f2fs_hash_t;
 /* MAX level for dir lookup */
 #define MAX_DIR_HASH_DEPTH	63
 
+/* MAX buckets in one level of dir */
+#define MAX_DIR_BUCKETS		(1 << ((MAX_DIR_HASH_DEPTH / 2) - 1))
+
 #define SIZE_OF_DIR_ENTRY	11	/* by byte */
 #define SIZE_OF_DENTRY_BITMAP	((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
 					BITS_PER_BYTE)

Signature · 14 lines

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Chao Yu

author

2014-05-27 08:49 UTC #2 lore raw

Hi changman,

Quoted 10 lines

-----Original Message-----
From: Changman Lee [mailto:[email protected]]
Sent: Tuesday, May 27, 2014 2:23 PM
To: Chao Yu
Cc: Jaegeuk Kim; [email protected]; [email protected]; [email protected]
Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid overflow when large directory feathure is enabled
Hi, Chao
Good catch. Please, modify Documentation/filesytems/f2fs.txt

Thank you for reminding me, I will add modification of f2fs.txt in the patch later.

Quoted 51 lines · Chao Yu

Quoted 49 lines

When large directory feathure is enable, We have one case which could cause overflow in dir_buckets() as following:
special case: level + dir_level >= 32 and level < MAX_DIR_HASH_DEPTH / 2.

Here we define MAX_DIR_BUCKETS to limit the return value when the condition could trigger potential overflow.

Signed-off-by Chao Yu <[email protected]>

---
 fs/f2fs/dir.c           |    4 ++--
 include/linux/f2fs_fs.h |    3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

fs/f2fs/dir.c +2 -2

index c3f1485..966acb0 100644
@@ -23,10 +23,10 @@ static unsigned long dir_blocks(struct inode *inode)
 
 static unsigned int dir_buckets(unsigned int level, int dir_level)
 {
-	if (level < MAX_DIR_HASH_DEPTH / 2)
+	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
 		return 1 << (level + dir_level);
 	else
-		return 1 << ((MAX_DIR_HASH_DEPTH / 2 + dir_level) - 1);
+		return MAX_DIR_BUCKETS;
 }
 
 static unsigned int bucket_blocks(unsigned int level)

include/linux/f2fs_fs.h +3 -1

index 8c03f71..ba6f312 100644
@@ -394,6 +394,9 @@ typedef __le32	f2fs_hash_t;
 /* MAX level for dir lookup */
 #define MAX_DIR_HASH_DEPTH	63
 
+/* MAX buckets in one level of dir */
+#define MAX_DIR_BUCKETS		(1 << ((MAX_DIR_HASH_DEPTH / 2) - 1))
+
 #define SIZE_OF_DIR_ENTRY	11	/* by byte */
 #define SIZE_OF_DENTRY_BITMAP	((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
 					BITS_PER_BYTE)
--

1.7.10.4

Quoted 10 lines

Quoted 10 lines
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_______________________________________________
Linux-f2fs-devel mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel