Hi,
I've spent the half night staring at the devilish my_getpwuid and my_getgrgid functions
trying to find out a way to avoid actual and future potential buffer overflow problems
without breaking existing code.
Finally I've found a not intrusive way to do this that surely doesn't break existing code
and fixes a couple of problems too.
The attached patch:
1) changes the behaviour of my_getpwuid and my_getgrgid to avoid potetntial buffer overflows
2) fixes all occurences of this function calls in tar.c , id.c , ls.c, whoami.c, logger.c, libbb.h.
3) The behaviour of tar, ls and logger is unchanged.
4) The behavior of ps with somewhat longer usernames messing up output is fixed.
5) The only bigger change was the increasing of size of the buffers in id.c to avoid
false negatives (unknown user: xxxxxx) with usernames longer than 8 chars.
The value i used ( 32 chars ) was taken from the tar header ( see gname and uname).
Maybe this buffers can be reduced a bit ( to 16 or whatever ), this is up to you.
6) The increase of size of the binary is not so dramatic:
size busybox
text data bss dec hex filename
239568 2300 36816 278684 4409c busybox
size busybox_fixed
text data bss dec hex filename
239616 2300 36816 278732 440cc busybox
7) The behaviour of whoami changed:
actually it prints out an username cut down to the size of the buffer.
This could be fixed by increasing the size of the buffer as in id.c or
avoid the use of my_getpwuid and use getpwuid directly instead.
Maybe this colud be also remain unchanged......
Please apply if you think it is ok to do so.
The diff applies on today's cvs tarball (2004-08-25).
Thanks in advance,
Ciao,
Tito
dev_t. This is especially important now that the user space concept of a dev_t
and the kernel concept of a dev_t are divergant. The only bit of user space
allowed to know the number of major and minor bits is include/sys/sysmacros.h
(i.e. part of libc). When used with a current C library and a 2.6.x kernel,
this fix should allow BusyBox to support wide device major/minor numbers.
-Erik
Hello,
I found and patched 2 more bugs. The first is a misplaced semi-colon. The second
one is a buffer overflow. I doubt the buffer overflow is triggered in real life.
But you never know what those wily hackers are up to.
Thanks,
Steve Grubb
This is a bulk spelling fix patch against busybox-1.00-pre10.
If anyone gets a corrupted copy (and cares), let me know and
I will make alternate arrangements.
Erik - please apply.
Authors - please check that I didn't corrupt any meaning.
Package importers - see if any of these changes should be
passed to the upstream authors.
I glossed over lots of sloppy capitalizations, missing apostrophes,
mixed American/British spellings, and German-style compound words.
What is "pretect redefined for test" in cmdedit.c?
Good luck on the 1.00 release!
- Larry
archive_xread can be replaced with bb_full_read, and archive_copy_file
with bb_copyfd*
bb_copyfd is split into two functions bb_copyfd_size and bb_copyfd_eof,
they share a common backend.
Need to chdir after the tar file is opened, so make common tar filename
parsing and send the file descriptor rather than filename to
writeTarFile.
Modify the verboseFlag operation to determine wether to display on
stderr or stdout at display time, simpler than doing it in tar_main.
bb-tar "cjf" does not create a valid tbz2-archive -- if fact the result is a
plain tar-file (no compression) -- but does not warn about the unrecognized
parameter combination "cj" (bb does not have bzip2-compression yet, right?).
to fix this I have added an error message stating this does not work.
He also reported
cosmetic: versose "-v" does not show any output when used with "create"
which I have now fixed as well.
-Erik
He took a look into the recent reports of tar problems, and found an obvious
typo in last_patch91 from vodz which converted tar to use bb_getopt_ulflags.
It seems that under busybox unstable, "tar -c -f - blabla" create
a tar file named "-" instead of writing to stdout.
The included patch should fix this.
New complex patch for decrease size devel version. Requires previous patch.
Also removed small problems from dutmp and tar applets.
Also includes vodz' last_patch61_2:
Last patch correcting comment for #endif and more integrated
with libbb (very reduce size if used "cat" applet also).
Requires last_patch61 for modutils/config.in.
Hi, Erik.
my_getpw(uid/gid) and applets used it have problem:
if username for uid not found, applets can`t detect it
(but code pessent). Also "%8ld " format is bad:
spaces not required (applets have self format
or spec format (tar applet) and overflow for "id" applet...)
This problem also pressent in stable version.
Patch for unstable in attach.
--w
vodz
with mode 0777 in all cases due to usask issues. Thanks to Matt Kraai for
noticing and spotting the culprit. This makes bb tar behave just like GNU
tar once again.
-Erik
change permissions on existing directories. This behavior is contrary to SUSv2
and contrary to GNU tar. Thanks to Matt Kraai for pointing this out. I should
have been much more careful about accepting such a patch.
-Erik
This way, we can new get rid of all that tedious #define rubbish we used to
need to enable specific messages. This way is enormously simpler, and as a
bonus also ends up saving us 96 bytes.
-Erik
