Bugtraq mailing list archives
Re: Shred 1.0 Bug Report
From: "Guenther H. Leber" <gleber () GAMS AT>
Date: Tue, 10 Oct 2000 23:50:09 +0200
On Tue, Oct 10, 2000 at 08:45:27AM -0700, Jeff Harlan wrote:
Greetings, Ran a test with Shred v1.0 and found some unexpected results. This utility is supposed to overwrite a file with several passes of different bit patterns followed by one random pattern. The file is then unlinked. This is supposed to make
[...] In main() the author of shred calls overwrite(char *filename) several times, which is supposed to write diffent patterns to the file. Unfortunately the code of overwrite() is as follows (from shred.c): 89 long overwrite( char *filename ) 90 { [...] 98 if( NULL == (fp = fopen( filename, "w" ) ) ) [...] The call to fopen is supposed to open the file, but it will open the file *and* truncate it to zero length instead (see fopen(3)). This causes the data blocks of the file to be freed and the patterns will be written to newly allocated data blocks on the disk. If the block allocation algorithm of the filesystem chooses the same block(s), which was/were freed by truncating the file, then this program would accidentially work as expected. -GünthER -- GünthER H. Leber @ home PGP KeyID: 1024/68279259 PGP Public Key: https://www.luga.at/pgppubkeys/68279259.asc PGP Fingerprint: 4B 12 AD B5 4E ED AB 56 F7 3F B2 02 25 FD 95 98
Current thread:
- Shred 1.0 Bug Report Jeff Harlan (Oct 10)
- Re: Shred 1.0 Bug Report Guenther H. Leber (Oct 10)
- Re: Shred 1.0 Bug Report Frank Wiles (Oct 11)
- Re: Shred 1.0 Bug Report M. Leo Cooper (Oct 11)
- Re: Shred 1.0 Bug Report Wietse Venema (Oct 11)
- Re: Shred 1.0 Bug Report Alfred Perlstein (Oct 12)
- Re: Shred 1.0 Bug Report Mitchell Blank Jr (Oct 13)
- Re: File "shredding" Kurt Seifried (Oct 13)
- Re: Shred 1.0 Bug Report Wietse Venema (Oct 11)
- Re: Shred 1.0 Bug Report M. Leo Cooper (Oct 11)
- Re: Shred 1.0 Bug Report Dan Kaminsky (Oct 12)
- Re: Shred 1.0 Bug Report Guenther H. Leber (Oct 10)