Hi, I've got an AIX 5.2 server running wu-ftp 2.6.2. I found the "patch" for wu-ftp in the www.wu-ftpd.org website. I modified my source as they indicated for the off-by-one vulnerability and the DOS vulnerability they described. I then re-compiled (./configure; make; make install). The problem is the new ftpd binary does not work correctly. When I use it, if I type "ls -l" (or ls -<any flag>) I get an error: 550 Not enough space. There's plenty of space in all file systems. Any advice on how to fix this problem or how to go about troubleshooting it? Vania --- Przemyslaw Frasunek <venglinat_private> wrote: > Użytkownik Janusz Niewiadomski napisał: > > This bug may be non-exploitable if size of the > buffer is greater than > > MAXPATHLEN characters. This may occur for example > if wu-ftpd is compiled > > with some versions of Linux kernel where PATH_MAX > (and MAXPATHLEN > > accordingly) is defined to be exactly 4095 > characters. In such cases, > > the buffer is padded with an extra byte because of > variable alignment > > which is a result of code optimization. > > Actually, this bug is (probably) also > non-exploitable when wu-ftpd is > compiled using the gcc 3.x, which aligns stack > variables in a different way: > > (gdb) b fb_realpath > Breakpoint 1 at 0x8063c72: file realpath.c, line > 103. > (gdb) cont > Continuing. > (gdb) x/bx &resolved[4096] > 0xbfffc770: 0x00 > (gdb) awatch *0xbfffc770 > Hardware access (read/write) watchpoint 2: > *3221210992 > (gdb) cont > Continuing. > Hardware access (read/write) watchpoint 2: > *3221210992 > > Value = 0 > 0x400d81d9 in strcat () from /lib/libc.so.6 > > In my example (wu-ftpd 2.6.2 compiled on Debian with > gcc 3.3.1), the > address of NULL-overflowed byte is 0xbfffc770 and > the saved %ebp is located > at 0xbfffc788: > > (gdb) info frame 2 > Stack frame at 0xbfffc788: > eip = 0x8063ae4 in wu_realpath (realpath.c:60); > saved eip 0x8053b35 > called by frame at 0xbfffe7d8, caller of frame at > 0xbfffb748 > source language c. > Arglist at 0xbfffc788, args: path=0x808cef0 'A' > <repeats 200 times>..., > resolved_path=0xbfffc7a0 "\001\001", > chroot_path=0x8082e60 "" > Locals at 0xbfffc788, Previous frame's sp in esp > Saved registers: > ebx at 0xbfffc784, ebp at 0xbfffc788, eip at > 0xbfffc78c > > I have tested the generic RedHat 8.0 (which provides > wu-ftpd-2.6.2-5 > compiled with gcc 3.x) and the behaviour was exactly > the same. > > Wu-ftpd suppiled with Debian Woody also seems to be > non-exploitable -- it's > compiled on kernel 2.2 with PATH_MAX 4095. > > -- > * Fido: 2:480/124 ** WWW: http://www.frasunek.com/ > ** NIC-HDL: PMF9-RIPE * > * Inet: przemyslawat_private ** keyId: 2578FCAD | > C0613BE3 | EC78FAB5 * > __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com
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