From: Steven J. Magnani <[email protected]> When extending a file, make sure that the pointer to the last written extent does not get adjusted into the header (tag) portion of an Allocation Extent Descriptor. Otherwise, a subsequent call to udf_update_exents() can clobber the AED's tagLocation field, replacing it with the logical block number of a file extent.
Signed-off-by: Steven J. Magnani <[email protected]> --- --- a/fs/udf/inode.c 2020-12-28 20:51:29.000000000 -0600 +++ b/fs/udf/inode.c 2021-01-01 19:20:37.163767576 -0600 @@ -547,11 +547,14 @@ static int udf_do_extend_file(struct ino udf_write_aext(inode, last_pos, &last_ext->extLocation, last_ext->extLength, 1); - /* - * We've rewritten the last extent but there may be empty - * indirect extent after it - enter it. - */ - udf_next_aext(inode, last_pos, &tmploc, &tmplen, 0); + + if (new_block_bytes || prealloc_len) { + /* + * We've rewritten the last extent but there may be empty + * indirect extent after it - enter it. + */ + udf_next_aext(inode, last_pos, &tmploc, &tmplen, 0); + } } /* Managed to do everything necessary? */
