commit d978216dea6b21ac38230a59d172139185a68dbd Author: Nick Mathewson nickm@torproject.org Date: Sun Dec 18 20:13:58 2016 -0500
Fix parsing bug with unecognized token at EOS
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 --- changes/bug21018 | 11 +++++++++++ src/or/routerparse.c | 6 +++--- 2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/changes/bug21018 b/changes/bug21018 new file mode 100644 index 0000000..49a8b47 --- /dev/null +++ b/changes/bug21018 @@ -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. diff --git a/src/or/routerparse.c b/src/or/routerparse.c index 176c16f..71373ce 100644 --- a/src/or/routerparse.c +++ b/src/or/routerparse.c @@ -3857,7 +3857,7 @@ get_next_token(memarea_t *area,
if (tok->tp == ERR_) { /* No keyword matched; call it an "K_opt" or "A_unrecognized" */ - if (**s == '@') + if (*s < eol && **s == '@') tok->tp = A_UNKNOWN_; else tok->tp = K_OPT; @@ -4863,7 +4863,7 @@ rend_decrypt_introduction_points(char **ipos_decrypted, crypto_cipher_free(cipher);
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, ipos_encrypted + 2 + client_entries_len, ipos_encrypted_size - 2 - client_entries_len); @@ -4895,7 +4895,7 @@ rend_decrypt_introduction_points(char **ipos_decrypted, "small."); 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, ipos_encrypted_size -