[PATCH] udf: NULL dereference at udf_symlink() on error

[Changwoo Min]

There is no check for udf_tgetblk(), which could return NULL, in udf_symlink(). 
So there is a possibility of returning NULL under heavy memory pressure and 
possibility of NULL dereference. 

Signed-off-by: Changwoo Min <changwoo.m@xxxxxxxxx>
---
 fs/udf/namei.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index 33b246b..ed2f221 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -902,6 +902,10 @@ static int udf_symlink(struct inode *dir, struct dentry *dentry,
 				iinfo->i_location.partitionReferenceNum,
 				0);
 		epos.bh = udf_tgetblk(sb, block);
+		if (!epos.bh) {
+			err = -ENOMEM;
+			goto out_no_entry;
+		}
 		lock_buffer(epos.bh);
 		memset(epos.bh->b_data, 0x00, bsize);
 		set_buffer_uptodate(epos.bh);
-- 
1.9.1

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