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Fix parsing bug with unecognized token at EOS

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In get_token(), we could read one byte past the end of the
region. This is only a big problem in the case where the region
itself is (a) potentially hostile, and (b) not explicitly
nul-terminated.

This patch fixes the underlying bug, and also makes sure that the
one remaining case of not-NUL-terminated potentially hostile data
gets NUL-terminated.

Fix for bug 21018, TROVE-2016-12-002, and CVE-2016-1254
This commit is contained in:
Nick Mathewson 2016-12-18 20:13:58 -05:00
parent 9db47e7921
commit d978216dea
2 changed files with 14 additions and 3 deletions
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11
changes/bug21018 Normal file
View File

@ -0,0 +1,11 @@
o Major bugfixes (parsing, security):
- Fix a bug in parsing that could cause clients to read a single
byte past the end of an allocated region. This bug could be
used to cause hardened clients (built with
--enable-expensive-hardening) to crash if they tried to visit
a hostile hidden service. Non-hardened clients are only
affected depending on the details of their platform's memory
allocator. Fixes bug 21018; bugfix on 0.2.0.8-alpha. Found by
using libFuzzer. Also tracked as TROVE-2016-12-002 and as
CVE-2016-1254.

6
src/or/routerparse.c
View File

@ -3857,7 +3857,7 @@ get_next_token(memarea_t *area,
if (tok->tp == ERR_) { if (tok->tp == ERR_) {
/* No keyword matched; call it an "K_opt" or "A_unrecognized" */ /* No keyword matched; call it an "K_opt" or "A_unrecognized" */
if (**s == '@') if (*s < eol && **s == '@')
tok->tp = A_UNKNOWN_; tok->tp = A_UNKNOWN_;
else else
tok->tp = K_OPT; tok->tp = K_OPT;
@ -4863,7 +4863,7 @@ rend_decrypt_introduction_points(char **ipos_decrypted,
crypto_cipher_free(cipher); crypto_cipher_free(cipher);
len = ipos_encrypted_size - 2 - client_entries_len - CIPHER_IV_LEN; len = ipos_encrypted_size - 2 - client_entries_len - CIPHER_IV_LEN;
dec = tor_malloc(len); dec = tor_malloc_zero(len + 1);
declen = crypto_cipher_decrypt_with_iv(session_key, dec, len, declen = crypto_cipher_decrypt_with_iv(session_key, dec, len,
ipos_encrypted + 2 + client_entries_len, ipos_encrypted + 2 + client_entries_len,
ipos_encrypted_size - 2 - client_entries_len); ipos_encrypted_size - 2 - client_entries_len);
@ -4895,7 +4895,7 @@ rend_decrypt_introduction_points(char **ipos_decrypted,
"small."); "small.");
return -1; return -1;
} }
dec = tor_malloc_zero(ipos_encrypted_size - CIPHER_IV_LEN - 1); dec = tor_malloc_zero(ipos_encrypted_size - CIPHER_IV_LEN - 1 + 1);
declen = crypto_cipher_decrypt_with_iv(descriptor_cookie, dec, declen = crypto_cipher_decrypt_with_iv(descriptor_cookie, dec,
ipos_encrypted_size - ipos_encrypted_size -