udf: fix possible leakage of blocks

We have to take care that when we call udf_discard_prealloc() from
udf_clear_inode() we have to write inode ourselves afterwards (otherwise,
some changes might be lost leading to leakage of blocks, use of free blocks
or improperly aligned extents).

Also udf_discard_prealloc() does two different things - it removes
preallocated blocks and truncates the last extent to exactly match i_size.
We move the latter functionality to udf_truncate_tail_extent(), call
udf_discard_prealloc() when last reference to a file is dropped and call
udf_truncate_tail_extent() when inode is being removed from inode cache
(udf_clear_inode() call).

We cannot call udf_truncate_tail_extent() earlier as subsequent open+write
would find the last block of the file mapped and happily write to the end
of it, although the last extent says it's shorter.

[akpm@linux-foundation.org: Make checkpatch.pl happier]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Sandeen <sandeen@sandeen.net>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 1f0129405cf47e636220a59ccd1e4f040940057d..bf7de0bdbab3b6554cbf7ba3eb20dc8ad92a7183 100644 (file)
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -100,14 +100,23 @@ void udf_delete_inode(struct inode * inode)
        clear_inode(inode);
 }
 
+/*
+ * If we are going to release inode from memory, we discard preallocation and
+ * truncate last inode extent to proper length. We could use drop_inode() but
+ * it's called under inode_lock and thus we cannot mark inode dirty there.  We
+ * use clear_inode() but we have to make sure to write inode as it's not written
+ * automatically.
+ */
 void udf_clear_inode(struct inode *inode)
 {
        if (!(inode->i_sb->s_flags & MS_RDONLY)) {
                lock_kernel();
+               /* Discard preallocation for directories, symlinks, etc. */
                udf_discard_prealloc(inode);
+               udf_truncate_tail_extent(inode);
                unlock_kernel();
+               write_inode_now(inode, 1);
        }
-
        kfree(UDF_I_DATA(inode));
        UDF_I_DATA(inode) = NULL;
 }

diff --git a/fs/udf/truncate.c b/fs/udf/truncate.c
index 77975ae291a55410c72db68025add299aa0c06f5..60d277644248617aee14d98ddff62cf0e11c8f6a 100644 (file)
--- a/fs/udf/truncate.c
+++ b/fs/udf/truncate.c
@@ -61,7 +61,11 @@ static void extent_trunc(struct inode * inode, struct extent_position *epos,
        }
 }
 
-void udf_discard_prealloc(struct inode * inode)
+/*
+ * Truncate the last extent to match i_size. This function assumes
+ * that preallocation extent is already truncated.
+ */
+void udf_truncate_tail_extent(struct inode *inode)
 {
        struct extent_position epos = { NULL, 0, {0, 0}};
        kernel_lb_addr eloc;
@@ -71,7 +75,10 @@ void udf_discard_prealloc(struct inode * inode)
        int adsize;
 
        if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB ||
-               inode->i_size == UDF_I_LENEXTENTS(inode))
+           inode->i_size == UDF_I_LENEXTENTS(inode))
+               return;
+       /* Are we going to delete the file anyway? */
+       if (inode->i_nlink == 0)
                return;
 
        if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
@@ -79,36 +86,76 @@ void udf_discard_prealloc(struct inode * inode)
        else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
                adsize = sizeof(long_ad);
        else
-               adsize = 0;
-
-       epos.block = UDF_I_LOCATION(inode);
+               BUG();
 
        /* Find the last extent in the file */
        while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1)
        {
                etype = netype;
                lbcount += elen;
-               if (lbcount > inode->i_size && lbcount - elen < inode->i_size)
-               {
-                       WARN_ON(lbcount - inode->i_size >= inode->i_sb->s_blocksize);
+               if (lbcount > inode->i_size) {
+                       if (lbcount - inode->i_size >= inode->i_sb->s_blocksize)
+                               printk(KERN_WARNING
+                                      "udf_truncate_tail_extent(): Too long "
+                                      "extent after EOF in inode %u: i_size: "
+                                      "%Ld lbcount: %Ld extent %u+%u\n",
+                                      (unsigned)inode->i_ino,
+                                      (long long)inode->i_size,
+                                      (long long)lbcount,
+                                      (unsigned)eloc.logicalBlockNum,
+                                      (unsigned)elen);
                        nelen = elen - (lbcount - inode->i_size);
                        epos.offset -= adsize;
                        extent_trunc(inode, &epos, eloc, etype, elen, nelen);
                        epos.offset += adsize;
-                       lbcount = inode->i_size;
+                       if (udf_next_aext(inode, &epos, &eloc, &elen, 1) != -1)
+                               printk(KERN_ERR "udf_truncate_tail_extent(): "
+                                      "Extent after EOF in inode %u.\n",
+                                      (unsigned)inode->i_ino);
+                       break;
                }
        }
+       /* This inode entry is in-memory only and thus we don't have to mark
+        * the inode dirty */
+       UDF_I_LENEXTENTS(inode) = inode->i_size;
+       brelse(epos.bh);
+}
+
+void udf_discard_prealloc(struct inode *inode)
+{
+       struct extent_position epos = { NULL, 0, {0, 0}};
+       kernel_lb_addr eloc;
+       uint32_t elen;
+       uint64_t lbcount = 0;
+       int8_t etype = -1, netype;
+       int adsize;
+
+       if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB ||
+               inode->i_size == UDF_I_LENEXTENTS(inode))
+               return;
+
+       if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
+               adsize = sizeof(short_ad);
+       else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
+               adsize = sizeof(long_ad);
+       else
+               adsize = 0;
+
+       epos.block = UDF_I_LOCATION(inode);
+
+       /* Find the last extent in the file */
+       while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
+               etype = netype;
+               lbcount += elen;
+       }
        if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
                epos.offset -= adsize;
                lbcount -= elen;
                extent_trunc(inode, &epos, eloc, etype, elen, 0);
-               if (!epos.bh)
-               {
+               if (!epos.bh) {
                        UDF_I_LENALLOC(inode) = epos.offset - udf_file_entry_alloc_offset(inode);
                        mark_inode_dirty(inode);
-               }
-               else
-               {
+               } else {
                        struct allocExtDesc *aed = (struct allocExtDesc *)(epos.bh->b_data);
                        aed->lengthAllocDescs = cpu_to_le32(epos.offset - sizeof(struct allocExtDesc));
                        if (!UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_STRICT) || UDF_SB_UDFREV(inode->i_sb) >= 0x0201)
@@ -118,9 +165,9 @@ void udf_discard_prealloc(struct inode * inode)
                        mark_buffer_dirty_inode(epos.bh, inode);
                }
        }
+       /* This inode entry is in-memory only and thus we don't have to mark
+        * the inode dirty */
        UDF_I_LENEXTENTS(inode) = lbcount;
-
-       WARN_ON(lbcount != inode->i_size);
        brelse(epos.bh);
 }
 

diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index 67ded289497cfc3ba1e88a6f67d86f0fa6685c5d..f581f2f69c0f3f85af7cb14b627d86661c6447f7 100644 (file)
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -146,6 +146,7 @@ extern void udf_free_inode(struct inode *);
 extern struct inode * udf_new_inode (struct inode *, int, int *);
 
 /* truncate.c */
+extern void udf_truncate_tail_extent(struct inode *);
 extern void udf_discard_prealloc(struct inode *);
 extern void udf_truncate_extents(struct inode *);