commit 950d890f77d8f060702b100e6075d5083d536577 Author: Nick Mathewson <nickm@torproject.org> Date: Mon Apr 15 15:33:09 2019 -0400 In warn_if_nul_found, log surrounding context. We need to encode here instead of doing escaped(), since fwict escaped() does not currently handle NUL bytes. Also, use warn_if_nul_found in more cases to avoid duplication. --- src/feature/nodelist/microdesc.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/src/feature/nodelist/microdesc.c b/src/feature/nodelist/microdesc.c index eaa7f0caf..f4fa8eeae 100644 --- a/src/feature/nodelist/microdesc.c +++ b/src/feature/nodelist/microdesc.c @@ -69,6 +69,8 @@ struct microdesc_cache_t { }; static microdesc_cache_t *get_microdesc_cache_noload(void); +static void warn_if_nul_found(const char *inp, size_t len, int64_t offset, + const char *activity); /** Helper: computes a hash of <b>md</b> to place it in a hash table. */ static inline unsigned int @@ -221,14 +223,8 @@ dump_microdescriptor(int fd, microdesc_t *md, size_t *annotation_len_out) } md->off = tor_fd_getpos(fd); - const char *nulpos = memchr(md->body, 0, md->bodylen); - if (BUG(nulpos)) { - log_warn(LD_BUG, "About to dump a NUL into a microdescriptor file. " - "offset %"PRId64", bodylen %"TOR_PRIuSZ", " - "nul position %"TOR_PRIuSZ".", - (int64_t)md->off, md->bodylen, - (size_t)(nulpos - md->body)); - } + warn_if_nul_found(md->body, md->bodylen, (int64_t) md->off, + "dumping a microdescriptor"); written = write_all_to_fd(fd, md->body, md->bodylen); if (written != (ssize_t)md->bodylen) { written = written < 0 ? 0 : written; @@ -489,13 +485,23 @@ microdesc_cache_clear(microdesc_cache_t *cache) } static void -warn_if_nul_found(const char *inp, size_t len, const char *description) +warn_if_nul_found(const char *inp, size_t len, int64_t offset, + const char *activity) { const char *nul_found = memchr(inp, 0, len); if (BUG(nul_found)) { - log_warn(LD_BUG, "Found unexpected NUL while reading %s, at " - "position %"TOR_PRIuSZ"/%"TOR_PRIuSZ".", - description, (nul_found - inp), len); + log_warn(LD_BUG, "Found unexpected NUL while %s, offset %"PRId64 + "at position %"TOR_PRIuSZ"/%"TOR_PRIuSZ".", + activity, offset, (nul_found - inp), len); + const char *start_excerpt_at, *eos = inp + len; + if ((nul_found - inp) >= 16) + start_excerpt_at = nul_found - 16; + else + start_excerpt_at = inp; + size_t excerpt_len = MIN(32, eos - start_excerpt_at); + char tmp[65]; + base16_encode(tmp, sizeof(tmp), start_excerpt_at, excerpt_len); + log_warn(LD_BUG, " surrounding string: %s", tmp); } } @@ -516,7 +522,7 @@ microdesc_cache_reload(microdesc_cache_t *cache) mm = cache->cache_content = tor_mmap_file(cache->cache_fname); if (mm) { - warn_if_nul_found(mm->data, mm->size, "microdesc cache"); + warn_if_nul_found(mm->data, mm->size, 0, "scanning microdesc cache"); added = microdescs_add_to_cache(cache, mm->data, mm->data+mm->size, SAVED_IN_CACHE, 0, -1, NULL); if (added) { @@ -529,8 +535,8 @@ microdesc_cache_reload(microdesc_cache_t *cache) RFTS_IGNORE_MISSING, &st); if (journal_content) { cache->journal_len = (size_t) st.st_size; - warn_if_nul_found(journal_content, cache->journal_len, - "microdesc journal"); + warn_if_nul_found(journal_content, cache->journal_len, 0, + "reading microdesc journal"); added = microdescs_add_to_cache(cache, journal_content, journal_content+st.st_size, SAVED_IN_JOURNAL, 0, -1, NULL);