Check for size overflow in tar header fields.
This prevents surprising outputs being created, e.g. this cpio tar
output with more than one file:
tar cf suffix.tar AUTHORS
dd if=/dev/zero seek=16G bs=1 count=0 of=suffix.tar
echo suffix.tar | cpio -H tar -o | tar tvf -
-rw-r--r-- 1000/1000 0 2019-08-30 16:40 suffix.tar
-rw-r--r-- thomas/thomas 161 2019-08-30 16:40 AUTHORS
Patch attached, but also at https://cement.retrofitta.se/tmp/cpio-tar.patch
--
☢ Thomas ☢
commit bc285942df401ea332667ce89f821648cc27d9cd
Author: Thomas Habets <hab...@google.com>
Date: Fri Aug 30 16:48:39 2019 +0100
Check for size overflow in tar header fields.
This prevents surprising outputs being created, e.g. this cpio tar
output with more than one file:
tar cf suffix.tar AUTHORS
dd if=/dev/zero seek=16G bs=1 count=0 of=suffix.tar
echo suffix.tar | cpio -H tar -o | tar tvf -
-rw-r--r-- 1000/1000 0 2019-08-30 16:40 suffix.tar
-rw-r--r-- thomas/thomas 161 2019-08-30 16:40 AUTHORS
diff --git a/src/copyout.c b/src/copyout.c
index 7532dac..22a3f9a 100644
--- a/src/copyout.c
+++ b/src/copyout.c
@@ -552,8 +552,7 @@ write_out_header (struct cpio_file_stat *file_hdr, int out_des)
error (0, 0, _("%s: file name too long"), file_hdr->c_name);
return 1;
}
- write_out_tar_header (file_hdr, out_des); /* FIXME: No error checking */
- return 0;
+ return write_out_tar_header (file_hdr, out_des);
case arf_binary:
return write_out_binary_header (makedev (file_hdr->c_rdev_maj,
diff --git a/src/extern.h b/src/extern.h
index 6fa2089..bb75b0b 100644
--- a/src/extern.h
+++ b/src/extern.h
@@ -144,7 +144,7 @@ int make_path (char *argpath, uid_t owner, gid_t group,
const char *verbose_fmt_string);
/* tar.c */
-void write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des);
+int write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des);
int null_block (long *block, int size);
void read_in_tar_header (struct cpio_file_stat *file_hdr, int in_des);
int otoa (char *s, unsigned long *n);
diff --git a/src/tar.c b/src/tar.c
index 0a34845..98ff74d 100644
--- a/src/tar.c
+++ b/src/tar.c
@@ -91,8 +91,9 @@ stash_tar_filename (char *prefix, char *filename)
sprintf (where, "%*lo ", digits - 2, value);
except that sprintf fills in the trailing NUL and we don't. */
-static void
-to_oct (register long value, register int digits, register char *where)
+static int
+to_oct_or_error (register long value, register int digits, register char *where,
+ const char *filename, const char *fieldname)
{
--digits; /* Leave the trailing NUL slot alone. */
@@ -103,10 +104,17 @@ to_oct (register long value, register int digits, register char *where)
value >>= 3;
}
while (digits > 0 && value != 0);
+ if (value > 0)
+ {
+ error (0, 0, _("%s: field width not sufficient for storing %s"),
+ filename, fieldname);
+ return 1;
+ }
/* Add leading zeroes, if necessary. */
while (digits > 0)
where[--digits] = '0';
+ return 0;
}
@@ -137,7 +145,7 @@ tar_checksum (struct tar_header *tar_hdr)
/* Write out header FILE_HDR, including the file name, to file
descriptor OUT_DES. */
-void
+int
write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des)
{
int name_len;
@@ -166,11 +174,16 @@ write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des)
/* Ustar standard (POSIX.1-1988) requires the mode to contain only 3 octal
digits */
- to_oct (file_hdr->c_mode & MODE_ALL, 8, tar_hdr->mode);
- to_oct (file_hdr->c_uid, 8, tar_hdr->uid);
- to_oct (file_hdr->c_gid, 8, tar_hdr->gid);
- to_oct (file_hdr->c_filesize, 12, tar_hdr->size);
- to_oct (file_hdr->c_mtime, 12, tar_hdr->mtime);
+ if (to_oct_or_error (file_hdr->c_mode & MODE_ALL, 8, tar_hdr->mode, file_hdr->c_name, _("mode")))
+ return 1;
+ if (to_oct_or_error (file_hdr->c_uid, 8, tar_hdr->uid, file_hdr->c_name, _("uid")))
+ return 1;
+ if (to_oct_or_error (file_hdr->c_gid, 8, tar_hdr->gid, file_hdr->c_name, _("gid")))
+ return 1;
+ if (to_oct_or_error (file_hdr->c_filesize, 12, tar_hdr->size, file_hdr->c_name, _("file size")))
+ return 1;
+ if (to_oct_or_error (file_hdr->c_mtime, 12, tar_hdr->mtime, file_hdr->c_name, _("modification time")))
+ return 1;
switch (file_hdr->c_mode & CP_IFMT)
{
@@ -182,7 +195,8 @@ write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des)
strncpy (tar_hdr->linkname, file_hdr->c_tar_linkname,
TARLINKNAMESIZE);
tar_hdr->typeflag = LNKTYPE;
- to_oct (0, 12, tar_hdr->size);
+ if (to_oct_or_error (0, 12, tar_hdr->size, file_hdr->c_name, _("file size")))
+ return 1;
}
else
tar_hdr->typeflag = REGTYPE;
@@ -208,7 +222,8 @@ write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des)
than TARLINKNAMESIZE. */
strncpy (tar_hdr->linkname, file_hdr->c_tar_linkname,
TARLINKNAMESIZE);
- to_oct (0, 12, tar_hdr->size);
+ if (to_oct_or_error (0, 12, tar_hdr->size, file_hdr->c_name, _("file size")))
+ return 1;
break;
#endif /* CP_IFLNK */
}
@@ -227,13 +242,17 @@ write_out_tar_header (struct cpio_file_stat *file_hdr, int out_des)
if (name)
strcpy (tar_hdr->gname, name);
- to_oct (file_hdr->c_rdev_maj, 8, tar_hdr->devmajor);
- to_oct (file_hdr->c_rdev_min, 8, tar_hdr->devminor);
+ if (to_oct_or_error (file_hdr->c_rdev_maj, 8, tar_hdr->devmajor, file_hdr->c_name, _("rdev major")))
+ return 1;
+ if (to_oct_or_error (file_hdr->c_rdev_min, 8, tar_hdr->devminor, file_hdr->c_name, _("rdev minor")))
+ return 1;
}
- to_oct (tar_checksum (tar_hdr), 8, tar_hdr->chksum);
+ if (to_oct_or_error (tar_checksum (tar_hdr), 8, tar_hdr->chksum, file_hdr->c_name, _("checksum")))
+ return 1;
tape_buffered_write ((char *) &tar_rec, out_des, TARRECORDSIZE);
+ return 0;
}
/* Return nonzero iff all the bytes in BLOCK are NUL.
