Control: tags -1 + patch [Phil Reynolds 2010-04-05] > When writing virtual images for later burning to DVDs, if the -C switch > to cdbackup is not used, the tracks in the images cannot be restored > using cdrestore as the CRC check fails. This applies whether the images > are on DVD or have been kept on a hard disc.
I wonder, could this be caused by a memory overflow in the CRC calculating code? If so, I propose this patch to fix it. Description: Make sure setting and reading CRC do not work past buffer size. The code used to store 8 bytes in a 4 byte space, and read 8 bytes from a 4 byte space on 64 bit platforms. Rewrite to use int32_t to ensure only 4 bytes are used. Author: Petter Reinholdtsen <p...@debian.org> Bug-Debian: https://bugs.debian.org/576520 Forwarded: no Last-Update: 2024-06-15 --- --- cdbackup-0.7.1.orig/cdbackup.c +++ cdbackup-0.7.1/cdbackup.c @@ -29,6 +29,7 @@ SUCH DAMAGE. #include <stdlib.h> #include <stdio.h> #include <stdarg.h> +#include <stdint.h> #include <unistd.h> #include <fcntl.h> #include <string.h> @@ -392,8 +393,8 @@ int backup(void) } } if(crc) { - int l=crc32(buffer,bytes+DBSIZE); - *((unsigned long *)(&buffer[CD_FRAMESIZE-4]))=l; + int32_t l=crc32(buffer,bytes+DBSIZE); + *((int32_t *)(&buffer[CD_FRAMESIZE-sizeof(l)]))=l; } Vwrite(buffer); grandTotal+=CD_FRAMESIZE; } while(db->status==0); --- cdbackup-0.7.1.orig/cdrestore.c +++ cdbackup-0.7.1/cdrestore.c @@ -28,6 +28,7 @@ SUCH DAMAGE. #include <stdio.h> #include <stdlib.h> +#include <stdint.h> #include <string.h> #include <unistd.h> #include <time.h> @@ -203,8 +204,8 @@ int restore(int disktrack) } if(db->flags&F_CRC) { - int l=crc32(buffer,size+DBSIZE); - if(*((unsigned long *)(&buffer[CD_FRAMESIZE-4]))!=l) { + int32_t l=crc32(buffer,size+DBSIZE); + if(*((int32_t *)(&buffer[CD_FRAMESIZE-sizeof(l)]))!=l) { if(verbose) fprintf(stderr,"%s: bad CRC checksum at %lld\n",prg_name,totalRead); serror("Bad checksum, block corrupted, restore failed"); } The patch is commited to the git repo on <URL:https://salsa.debian.org/debian/cdbackup >, but not uploaded as I could like to know if it solve this bug first. Are you able to test it? -- Happy hacking Petter Reinholdtsen
