-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 03/ 9/16 04:31 PM, Dimitry Andric wrote: > On 09 Mar 2016, at 21:39, Dimitry Andric <d...@freebsd.org> wrote: >> >> On 09 Mar 2016, at 10:16, Xin Li <delp...@delphij.net> wrote: >>> >>> FYI -- I can confirm that libcrypto is broken and have a >>> reliable way to trigger it. >>> >>> So far I was able to narrow down this to this change and here >>> is a temporary workaround (which will reintroduce >>> CVE-2016-0702). >>> >>> Cheers, <bn-revert.diff> >> >> FWIW, before the workaround I get this from valgrind: >> >> ==10050== Invalid read of size 8 ==10050== at 0x6BA3438: >> MOD_EXP_CTIME_COPY_FROM_PREBUF (bn_exp.c:585) ==10050== by >> 0x6BA3438: BN_mod_exp_mont_consttime (bn_exp.c:760) ==10050== by >> 0x6B84AB7: ??? (dh_key.c:156) ==10050== by 0x4E4550B: >> ssh_dh_gen_key (in /usr/lib/private/libssh.so.5) ==10050== by >> 0x42AEBF: kexgex_server (kexgexs.c:115) ==10050== by >> 0x4E545FE: ssh_kex_input_kexinit (in >> /usr/lib/private/libssh.so.5) ==10050== by 0x4E54BBE: >> ssh_dispatch_run (in /usr/lib/private/libssh.so.5) ==10050== by >> 0x41085C: do_ssh2_kex (sshd.c:2559) ==10050== by 0x41085C: >> main (sshd.c:2162) ==10050== Address 0x2078f3580 is not >> stack'd, malloc'd or (recently) free'd ==10050== ==10050== >> ==10050== Process terminating with default action of signal 11 >> (SIGSEGV): dumping core ==10050== Access not within mapped >> region at address 0x2078F3580 ==10050== at 0x6BA3438: >> MOD_EXP_CTIME_COPY_FROM_PREBUF (bn_exp.c:585) ==10050== by >> 0x6BA3438: BN_mod_exp_mont_consttime (bn_exp.c:760) ==10050== by >> 0x6B84AB7: ??? (dh_key.c:156) ==10050== by 0x4E4550B: >> ssh_dh_gen_key (in /usr/lib/private/libssh.so.5) ==10050== by >> 0x42AEBF: kexgex_server (kexgexs.c:115) ==10050== by >> 0x4E545FE: ssh_kex_input_kexinit (in >> /usr/lib/private/libssh.so.5) ==10050== by 0x4E54BBE: >> ssh_dispatch_run (in /usr/lib/private/libssh.so.5) ==10050== by >> 0x41085C: do_ssh2_kex (sshd.c:2559) ==10050== by 0x41085C: >> main (sshd.c:2162) ==10050== If you believe this happened as a >> result of a stack ==10050== overflow in your program's main >> thread (unlikely but ==10050== possible), you can try to >> increase the size of the ==10050== main thread stack using the >> --main-stacksize= flag. ==10050== The main thread stack size >> used in this run was 16777216. > > I think this is a possible fix (it works for me, at least): > > Index: crypto/openssl/crypto/bn/bn_exp.c > =================================================================== > > > > > - --- crypto/openssl/crypto/bn/bn_exp.c (revision 296469) > +++ crypto/openssl/crypto/bn/bn_exp.c (working copy) @@ -758,7 > +758,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BI * > Fetch the appropriate pre-computed value from the pre-buf */ if > (!MOD_EXP_CTIME_COPY_FROM_PREBUF - (computeTemp, top, > powerbuf, wvalue, numPowers)) + (computeTemp, top, > powerbuf, wvalue, window)) goto err; > > /* Multiply the result into the intermediate result */ > > Can people experiencing this problem please apply the above diff to > their openssl, rebuild secure/lib/libcrypto, install it, then > restart sshd and/or whatever daemon you have seen the crashes > with?
[My PC had multiple PSU failures and I just recovered from the disaster. I am very sorry for the late response.] I haven't tested it but it looks correct. I don't know how I missed it in the first place. :-( JK -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJW4KFSAAoJEHyflib82/FGGt8H/iaaxbks7copI9O4oCs229RG UlLxx1XsrYkdStEqJHg4OXgXr6kIdkSpBBJjYs3DlOFKL5Vin0PTenfDV0i0a0/l MbawMhWX6xhNaUKSHVguXJeGZUGT4pYQe6pZoZYT2ZrAq5eEavk/y0qlwPK4xV50 A/xXsfgLGwruMZjJ4JJ7N4CZMByyKu7jAhnveDFS3A87HOve48HEGpHY/UDmWvZ1 t1JX0e7ZCO+frHAwYdBkMG9w4ozQ26PjGTyJuL/852GORaxt+5kZ4Uj2/jLjxIIj pnFJ1CrzjFKqX3+03QaOi+hFlBPyQ/CMyMg03fO5MQqTys3ehObujRmfE1mhCZs= =KShP -----END PGP SIGNATURE----- _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"