SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

basic/log: make sure header is printed correctly, add test

Browse Source 
If log_do_header() was called with overly long parameters, it'd generate
improper output. Essentially, it'd be truncated at random point, in particular
missing a newline at the end, so it'd run with the next field, usually MESSAGE=.

log_do_header is called with parameters from compiled code (file name, lien
nubmer, etc), so in practice this was unlikely to ever be a problem, but it is
possible. In particular, if systemd was compiled from sources in some deeply
nested directory (which happens for example in mock and other build roots), the
filename could be very long.

As a safety measure, let's truncate all parameters to 256 bytes. So we have
5 fields which are 256 bytes (plus the field name prefix), and a few other
fields with fixed width. This must always fit in the 2048 byte buffer.
I don't think there's much gain in calculating the required length precisely,
since it's a lot of fields and a few bytes allocated on the stack don't matter.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2018-02-23 11:13:42 +01:00
parent 4dd09c6a1f
commit f8e6f4aaed
2 changed files with 65 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/basic/log.c
+33 -31
View File
@@ -498,38 +498,40 @@ static int log_do_header(
const char *file, int line, const char *func,
const char *object_field, const char *object,
const char *extra_field, const char *extra) {
int r;
snprintf(header, size,
"PRIORITY=%i\n"
"SYSLOG_FACILITY=%i\n"
"%s%s%s"
"%s%.*i%s"
"%s%s%s"
"%s%.*i%s"
"%s%s%s"
"%s%s%s"
"SYSLOG_IDENTIFIER=%s\n",
LOG_PRI(level),
LOG_FAC(level),
isempty(file) ? "" : "CODE_FILE=",
isempty(file) ? "" : file,
isempty(file) ? "" : "\n",
line ? "CODE_LINE=" : "",
line ? 1 : 0, line, /* %.0d means no output too, special case for 0 */
line ? "\n" : "",
isempty(func) ? "" : "CODE_FUNC=",
isempty(func) ? "" : func,
isempty(func) ? "" : "\n",
error ? "ERRNO=" : "",
error ? 1 : 0, error,
error ? "\n" : "",
isempty(object) ? "" : object_field,
isempty(object) ? "" : object,
isempty(object) ? "" : "\n",
isempty(extra) ? "" : extra_field,
isempty(extra) ? "" : extra,
isempty(extra) ? "" : "\n",
program_invocation_short_name);
r = snprintf(header, size,
"PRIORITY=%i\n"
"SYSLOG_FACILITY=%i\n"
"%s%.256s%s" /* CODE_FILE */
"%s%.*i%s" /* CODE_LINE */
"%s%.256s%s" /* CODE_FUNC */
"%s%.*i%s" /* ERRNO */
"%s%.256s%s" /* object */
"%s%.256s%s" /* extra */
"SYSLOG_IDENTIFIER=%.256s\n",
LOG_PRI(level),
LOG_FAC(level),
isempty(file) ? "" : "CODE_FILE=",
isempty(file) ? "" : file,
isempty(file) ? "" : "\n",
line ? "CODE_LINE=" : "",
line ? 1 : 0, line, /* %.0d means no output too, special case for 0 */
line ? "\n" : "",
isempty(func) ? "" : "CODE_FUNC=",
isempty(func) ? "" : func,
isempty(func) ? "" : "\n",
error ? "ERRNO=" : "",
error ? 1 : 0, error,
error ? "\n" : "",
isempty(object) ? "" : object_field,
isempty(object) ? "" : object,
isempty(object) ? "" : "\n",
isempty(extra) ? "" : extra_field,
isempty(extra) ? "" : extra,
isempty(extra) ? "" : "\n",
program_invocation_short_name);
assert((size_t) r < size);
return 0;
}