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| author | Nick Mathewson <nickm@torproject.org> | 2018-10-25 09:06:13 -0400 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2018-10-25 09:06:13 -0400 |
| commit | 368413a321a65234c0256c4ea80c613207cf7587 (patch) | |
| tree | 63b88d347e2f9706494c7d210002c6ed1451afd1 | |
| parent | 5b28190c67ac6828e588c0ec54fe88eab0fb45fb (diff) | |
| download | tor-368413a321a65234c0256c4ea80c613207cf7587.tar.gz tor-368413a321a65234c0256c4ea80c613207cf7587.zip | |
Fix possible UB in an end-of-string check in get_next_token().
Remember, you can't check to see if there are N bytes left in a
buffer by doing (buf + N < end), since the buf + N computation might
take you off the end of the buffer and result in undefined behavior.
Fixes 28202; bugfix on 0.2.0.3-alpha.
| -rw-r--r-- | changes/bug28202 | 4 | ||||
| -rw-r--r-- | src/or/routerparse.c | 2 |
2 files changed, 5 insertions, 1 deletions
diff --git a/changes/bug28202 b/changes/bug28202 new file mode 100644 index 0000000000..182daac4f1 --- /dev/null +++ b/changes/bug28202 @@ -0,0 +1,4 @@ + o Minor bugfixes (C correctness): + - Avoid undefined behavior in an end-of-string check when parsing the + BEGIN line in a directory object. Fixes bug 28202; bugfix on + 0.2.0.3-alpha. diff --git a/src/or/routerparse.c b/src/or/routerparse.c index 521e237be2..063cbbcdaf 100644 --- a/src/or/routerparse.c +++ b/src/or/routerparse.c @@ -4964,7 +4964,7 @@ get_next_token(memarea_t *area, goto check_object; obstart = *s; /* Set obstart to start of object spec */ - if (*s+16 >= eol || memchr(*s+11,'\0',eol-*s-16) || /* no short lines, */ + if (eol - *s <= 16 || memchr(*s+11,'\0',eol-*s-16) || /* no short lines, */ strcmp_len(eol-5, "-----", 5) || /* nuls or invalid endings */ (eol-*s) > MAX_UNPARSED_OBJECT_SIZE) { /* name too long */ RET_ERR("Malformed object: bad begin line"); |