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In warn_if_nul_found, log surrounding context.

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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.
This commit is contained in:
Nick Mathewson 2019-04-15 15:33:09 -04:00
parent 0c42ddf28c
commit 950d890f77
1 changed files with 21 additions and 15 deletions
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36
src/feature/nodelist/microdesc.c
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@ -69,6 +69,8 @@ struct microdesc_cache_t {
}; };
static microdesc_cache_t *get_microdesc_cache_noload(void); 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. */ /** Helper: computes a hash of <b>md</b> to place it in a hash table. */
static inline unsigned int 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); md->off = tor_fd_getpos(fd);
const char *nulpos = memchr(md->body, 0, md->bodylen); warn_if_nul_found(md->body, md->bodylen, (int64_t) md->off,
if (BUG(nulpos)) { "dumping a microdescriptor");
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));
}
written = write_all_to_fd(fd, md->body, md->bodylen); written = write_all_to_fd(fd, md->body, md->bodylen);
if (written != (ssize_t)md->bodylen) { if (written != (ssize_t)md->bodylen) {
written = written < 0 ? 0 : written; written = written < 0 ? 0 : written;
@ -489,13 +485,23 @@ microdesc_cache_clear(microdesc_cache_t *cache)
} }
static void 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); const char *nul_found = memchr(inp, 0, len);
if (BUG(nul_found)) { if (BUG(nul_found)) {
log_warn(LD_BUG, "Found unexpected NUL while reading %s, at " log_warn(LD_BUG, "Found unexpected NUL while %s, offset %"PRId64
"position %"TOR_PRIuSZ"/%"TOR_PRIuSZ".", "at position %"TOR_PRIuSZ"/%"TOR_PRIuSZ".",
description, (nul_found - inp), len); 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); mm = cache->cache_content = tor_mmap_file(cache->cache_fname);
if (mm) { 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, added = microdescs_add_to_cache(cache, mm->data, mm->data+mm->size,
SAVED_IN_CACHE, 0, -1, NULL); SAVED_IN_CACHE, 0, -1, NULL);
if (added) { if (added) {
@ -529,8 +535,8 @@ microdesc_cache_reload(microdesc_cache_t *cache)
RFTS_IGNORE_MISSING, &st); RFTS_IGNORE_MISSING, &st);
if (journal_content) { if (journal_content) {
cache->journal_len = (size_t) st.st_size; cache->journal_len = (size_t) st.st_size;
warn_if_nul_found(journal_content, cache->journal_len, warn_if_nul_found(journal_content, cache->journal_len, 0,
"microdesc journal"); "reading microdesc journal");
added = microdescs_add_to_cache(cache, journal_content, added = microdescs_add_to_cache(cache, journal_content,
journal_content+st.st_size, journal_content+st.st_size,
SAVED_IN_JOURNAL, 0, -1, NULL); SAVED_IN_JOURNAL, 0, -1, NULL);