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
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
make busybox be more uClinux friendly. I also adjusted Config.h for
uClinux so it will automagically disable apps the arn't going to
work without fork() and such.
-Erik
busybox.h which slowed compiles. I left only what was needed and then fixed up
all the apps to include their own header files. I also fixed naming for pwd.h
and grp.h functions. Tested to compile and run with libc5, glibc, and uClibc.
-Erik
options, logger is better behaved and has a "-t" option now. init now supports
the kernel chroot patch, so you can chroot to a new device and umount the old
root.
-Erik
