1 files changed, 46 insertions, 11 deletions

diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c
index 6fb7945c1e6e..ac10ca939f26 100644
--- a/fs/udf/symlink.c
+++ b/fs/udf/symlink.c
@@ -30,49 +30,73 @@
 #include <linux/buffer_head.h>
 #include "udf_i.h"
 
-static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
-                           int fromlen, unsigned char *to)
+static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
+                          int fromlen, unsigned char *to, int tolen)
 {
         struct pathComponent *pc;
         int elen = 0;
+        int comp_len;
         unsigned char *p = to;
 
+        /* Reserve one byte for terminating \0 */
+        tolen--;
         while (elen < fromlen) {
                 pc = (struct pathComponent *)(from + elen);
+                elen += sizeof(struct pathComponent);
                 switch (pc->componentType) {
                 case 1:
                         /*
                          * Symlink points to some place which should be agreed
                          * upon between originator and receiver of the media. Ignore.
                          */
-                        if (pc->lengthComponentIdent > 0)
+                        if (pc->lengthComponentIdent > 0) {
+                                elen += pc->lengthComponentIdent;
                                 break;
+                        }
                         /* Fall through */
                 case 2:
+                        if (tolen == 0)
+                                return -ENAMETOOLONG;
                         p = to;
                         *p++ = '/';
+                        tolen--;
                         break;
                 case 3:
+                        if (tolen < 3)
+                                return -ENAMETOOLONG;
                         memcpy(p, "../", 3);
                         p += 3;
+                        tolen -= 3;
                         break;
                 case 4:
+                        if (tolen < 2)
+                                return -ENAMETOOLONG;
                         memcpy(p, "./", 2);
                         p += 2;
+                        tolen -= 2;
                         /* that would be . - just ignore */
                         break;
                 case 5:
-                        p += udf_get_filename(sb, pc->componentIdent, p,
-                                              pc->lengthComponentIdent);
+                        elen += pc->lengthComponentIdent;
+                        if (elen > fromlen)
+                                return -EIO;
+                        comp_len = udf_get_filename(sb, pc->componentIdent,
+                                                    pc->lengthComponentIdent,
+                                                    p, tolen);
+                        p += comp_len;
+                        tolen -= comp_len;
+                        if (tolen == 0)
+                                return -ENAMETOOLONG;
                         *p++ = '/';
+                        tolen--;
                         break;
                 }
-                elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
         }
         if (p > to + 1)
                 p[-1] = '\0';
         else
                 p[0] = '\0';
+        return 0;
 }
 
 static int udf_symlink_filler(struct file *file, struct page *page)
@@ -80,11 +104,17 @@ static int udf_symlink_filler(struct file *file, struct page *page)
         struct inode *inode = page->mapping->host;
         struct buffer_head *bh = NULL;
         unsigned char *symlink;
-        int err = -EIO;
+        int err;
         unsigned char *p = kmap(page);
         struct udf_inode_info *iinfo;
         uint32_t pos;
 
+        /* We don't support symlinks longer than one block */
+        if (inode->i_size > inode->i_sb->s_blocksize) {
+                err = -ENAMETOOLONG;
+                goto out_unmap;
+        }
+
         iinfo = UDF_I(inode);
         pos = udf_block_map(inode, 0);
 
@@ -94,14 +124,18 @@ static int udf_symlink_filler(struct file *file, struct page *page)
         } else {
                 bh = sb_bread(inode->i_sb, pos);
 
-                if (!bh)
-                        goto out;
+                if (!bh) {
+                        err = -EIO;
+                        goto out_unlock_inode;
+                }
 
                 symlink = bh->b_data;
         }
 
-        udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
+        err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
         brelse(bh);
+        if (err)
+                goto out_unlock_inode;
 
         up_read(&iinfo->i_data_sem);
         SetPageUptodate(page);
@@ -109,9 +143,10 @@ static int udf_symlink_filler(struct file *file, struct page *page)
         unlock_page(page);
         return 0;
 
-out:
+out_unlock_inode:
         up_read(&iinfo->i_data_sem);
         SetPageError(page);
+out_unmap:
         kunmap(page);
         unlock_page(page);
         return err;