[PATCH 2/2] Fix possible NULL pointer dereference in udf_table_free_blocks()

[Jan Kara <jack@suse.cz>]

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  Hello,

  fix possible NULL pointer dereference in UDF block freeing code. The description in the
header of the patch has more details. Andrew, please apply. Thanks.

										Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs

[-- Attachment #2: udf-2.6.23-rc3-NULL_dereference.diff --]
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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>
 
diff -rupX /home/jack/.kerndiffexclude linux-2.6.23-rc3/fs/udf/balloc.c linux-2.6.23-rc3-1-udf_fix/fs/udf/balloc.c
--- linux-2.6.23-rc3/fs/udf/balloc.c	2007-08-21 14:11:44.000000000 +0200
+++ linux-2.6.23-rc3-1-udf_fix/fs/udf/balloc.c	2007-08-21 14:28:31.000000000 +0200
@@ -540,26 +540,24 @@ static void udf_table_free_blocks(struct
 			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,