hfs: add error checking for hfs_find_init()

hfs_find_init() may fail with ENOMEM, but there are places, where the
returned value is not checked.  The consequences can be very unpleasant,
e.g.  kfree uninitialized pointer and inappropriate mutex unlocking.

The patch adds checks for errors in hfs_find_init().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 15 deletions

diff --git a/fs/hfs/extent.c b/fs/hfs/extent.c
index a67955a0c36f..813447b5b052 100644
--- a/fs/hfs/extent.c
+++ b/fs/hfs/extent.c
@@ -107,7 +107,7 @@ static u16 hfs_ext_lastblock(struct hfs_extent *ext)
 	return be16_to_cpu(ext->block) + be16_to_cpu(ext->count);
 }
 
-static void __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd)
+static int __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd)
 {
 	int res;
 
@@ -116,26 +116,31 @@ static void __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd
 	res = hfs_brec_find(fd);
 	if (HFS_I(inode)->flags & HFS_FLG_EXT_NEW) {
 		if (res != -ENOENT)
-			return;
+			return res;
 		hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec));
 		HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
 	} else {
 		if (res)
-			return;
+			return res;
 		hfs_bnode_write(fd->bnode, HFS_I(inode)->cached_extents, fd->entryoffset, fd->entrylength);
 		HFS_I(inode)->flags &= ~HFS_FLG_EXT_DIRTY;
 	}
+	return 0;
 }
 
-void hfs_ext_write_extent(struct inode *inode)
+int hfs_ext_write_extent(struct inode *inode)
 {
 	struct hfs_find_data fd;
+	int res = 0;
 
 	if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
-		hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
-		__hfs_ext_write_extent(inode, &fd);
+		res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
+		if (res)
+			return res;
+		res = __hfs_ext_write_extent(inode, &fd);
 		hfs_find_exit(&fd);
 	}
+	return res;
 }
 
 static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent,
@@ -161,8 +166,11 @@ static inline int __hfs_ext_cache_extent(struct hfs_find_data *fd, struct inode
 {
 	int res;
 
-	if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY)
-		__hfs_ext_write_extent(inode, fd);
+	if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
+		res = __hfs_ext_write_extent(inode, fd);
+		if (res)
+			return res;
+	}
 
 	res = __hfs_ext_read_extent(fd, HFS_I(inode)->cached_extents, inode->i_ino,
 				    block, HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
@@ -185,9 +193,11 @@ static int hfs_ext_read_extent(struct inode *inode, u16 block)
 	    block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks)
 		return 0;
 
-	hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
-	res = __hfs_ext_cache_extent(&fd, inode, block);
-	hfs_find_exit(&fd);
+	res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
+	if (!res) {
+		res = __hfs_ext_cache_extent(&fd, inode, block);
+		hfs_find_exit(&fd);
+	}
 	return res;
 }
 
@@ -298,7 +308,9 @@ int hfs_free_fork(struct super_block *sb, struct hfs_cat_file *file, int type)
 	if (total_blocks == blocks)
 		return 0;
 
-	hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
+	res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
+	if (res)
+		return res;
 	do {
 		res = __hfs_ext_read_extent(&fd, extent, cnid, total_blocks, type);
 		if (res)
@@ -438,7 +450,9 @@ out:
 
 insert_extent:
 	dprint(DBG_EXTENT, "insert new extent\n");
-	hfs_ext_write_extent(inode);
+	res = hfs_ext_write_extent(inode);
+	if (res)
+		goto out;
 
 	memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
 	HFS_I(inode)->cached_extents[0].block = cpu_to_be16(start);
@@ -466,7 +480,6 @@ void hfs_file_truncate(struct inode *inode)
 		struct address_space *mapping = inode->i_mapping;
 		void *fsdata;
 		struct page *page;
-		int res;
 
 		/* XXX: Can use generic_cont_expand? */
 		size = inode->i_size - 1;
@@ -488,7 +501,12 @@ void hfs_file_truncate(struct inode *inode)
 		goto out;
 
 	mutex_lock(&HFS_I(inode)->extents_lock);
-	hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
+	res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
+	if (res) {
+		mutex_unlock(&HFS_I(inode)->extents_lock);
+		/* XXX: We lack error handling of hfs_file_truncate() */
+		return;
+	}
 	while (1) {
 		if (alloc_cnt == HFS_I(inode)->first_blocks) {
 			hfs_free_extents(sb, HFS_I(inode)->first_extents,