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Thou shalt not overflow even stupidly small buffers

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This commit is contained in:
Robert Ransom 2011-02-04 05:50:44 -08:00
parent 89ee779f92
commit 0ab8b7c0f2
1 changed files with 10 additions and 0 deletions
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10
src/common/log.c
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@ -223,21 +223,31 @@ format_msg(char *buf, size_t buf_len,
size_t n; size_t n;
int r; int r;
char *end_of_prefix; char *end_of_prefix;
char *buf_end;
assert(buf_len >= 16); /* prevent integer underflow and general stupidity */ assert(buf_len >= 16); /* prevent integer underflow and general stupidity */
buf_len -= 2; /* subtract 2 characters so we have room for \n\0 */ buf_len -= 2; /* subtract 2 characters so we have room for \n\0 */
buf_end = buf+buf_len; /* point *after* the last char we can write to */
n = _log_prefix(buf, buf_len, severity); n = _log_prefix(buf, buf_len, severity);
end_of_prefix = buf+n; end_of_prefix = buf+n;
if (log_domains_are_logged) { if (log_domains_are_logged) {
char *cp = buf+n; char *cp = buf+n;
if (cp == buf_end) goto format_msg_no_room_for_domains;
*cp++ = '{'; *cp++ = '{';
if (cp == buf_end) goto format_msg_no_room_for_domains;
cp = domain_to_string(domain, cp, (buf+buf_len-cp)); cp = domain_to_string(domain, cp, (buf+buf_len-cp));
if (cp == buf_end) goto format_msg_no_room_for_domains;
*cp++ = '}'; *cp++ = '}';
if (cp == buf_end) goto format_msg_no_room_for_domains;
*cp++ = ' '; *cp++ = ' ';
if (cp == buf_end) goto format_msg_no_room_for_domains;
end_of_prefix = cp; end_of_prefix = cp;
n = cp-buf; n = cp-buf;
format_msg_no_room_for_domains:
/* This will leave end_of_prefix and n unchanged, and thus cause
* whatever log domain string we had written to be clobbered. */
} }
if (funcname && should_log_function_name(domain, severity)) { if (funcname && should_log_function_name(domain, severity)) {