Fix possible NULL pointer dereference in udf_table_free_blocks()

Fix possible NULL pointer dereference when freeing blocks in case table of
free space is used.  Also fix handling of the case when we need to move
extent from one block to another one to make space for indirect extent.
BTW: Nobody seem to have ever used this code.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 6 deletions

diff --git a/fs/udf/balloc.c b/fs/udf/balloc.c
index 276f7207a564..87e87dcd3f9c 100644
--- a/fs/udf/balloc.c
+++ b/fs/udf/balloc.c
@@ -540,26 +540,24 @@ static void udf_table_free_blocks(struct super_block *sb,
                         if (epos.offset + adsize > sb->s_blocksize) {
                                 loffset = epos.offset;
                                 aed->lengthAllocDescs = cpu_to_le32(adsize);
-                                sptr = UDF_I_DATA(inode) + epos.offset -
-                                        udf_file_entry_alloc_offset(inode) +
-                                        UDF_I_LENEATTR(inode) - adsize;
+                                sptr = UDF_I_DATA(table) + epos.offset - adsize;
                                 dptr = epos.bh->b_data + sizeof(struct allocExtDesc);
                                 memcpy(dptr, sptr, adsize);
                                 epos.offset = sizeof(struct allocExtDesc) + adsize;
                         } else {
                                 loffset = epos.offset + adsize;
                                 aed->lengthAllocDescs = cpu_to_le32(0);
-                                sptr = oepos.bh->b_data + epos.offset;
-                                epos.offset = sizeof(struct allocExtDesc);
-
                                 if (oepos.bh) {
+                                        sptr = oepos.bh->b_data + epos.offset;
                                         aed = (struct allocExtDesc *)oepos.bh->b_data;
                                         aed->lengthAllocDescs =
                                                 cpu_to_le32(le32_to_cpu(aed->lengthAllocDescs) + adsize);
                                 } else {
+                                        sptr = UDF_I_DATA(table) + epos.offset;
                                         UDF_I_LENALLOC(table) += adsize;
                                         mark_inode_dirty(table);
                                 }
+                                epos.offset = sizeof(struct allocExtDesc);
                         }
                         if (UDF_SB_UDFREV(sb) >= 0x0200)
                                 udf_new_tag(epos.bh->b_data, TAG_IDENT_AED, 3, 1,