The parse_ns_duration() function currently uses prefix matching for detecting time units. This approach is problematic as it silently accepts malformed strings such as "100nsx" or "100us_invalid" by ignoring the trailing characters, leading to potential configuration errors.
Introduce a match_time_unit() helper that checks the suffix matches exactly and is followed by either end-of-string or a ':' delimiter. The ':' is needed because parse_ns_duration() is also called from get_long_ns_after_colon() when parsing SCHED_DEADLINE priority specifications in the format "d:runtime:period" (e.g., "d:10ms:100ms"). A plain strcmp() would reject valid deadline strings because the suffix "ms" is followed by ":100ms", not end-of-string. Similarly, strncmp_static() would fail because ARRAY_SIZE() includes the NUL terminator, making it equivalent to strcmp() for this comparison. The match_time_unit() helper solves both problems: it rejects malformed input like "100msx" while correctly handling the colon-delimited deadline format. Signed-off-by: Wander Lairson Costa <[email protected]> --- tools/tracing/rtla/src/utils.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c index 486d96e8290fb..c3ed9089e7260 100644 --- a/tools/tracing/rtla/src/utils.c +++ b/tools/tracing/rtla/src/utils.c @@ -200,6 +200,21 @@ long parse_seconds_duration(char *val) return t; } +/* + * match_time_unit - check if str starts with unit followed by end-of-string or ':' + * + * This allows the time unit parser to work both in standalone duration strings + * like "100ms" and in colon-delimited SCHED_DEADLINE specifications like + * "d:10ms:100ms", while still rejecting malformed input like "100msx". + */ +static bool match_time_unit(const char *str, const char *unit) +{ + size_t len = strlen(unit); + + return strncmp(str, unit, len) == 0 && + (str[len] == '\0' || str[len] == ':'); +} + /* * parse_ns_duration - parse duration with ns/us/ms/s converting it to nanoseconds */ @@ -211,15 +226,15 @@ long parse_ns_duration(char *val) t = strtol(val, &end, 10); if (end) { - if (!strncmp(end, "ns", 2)) { + if (match_time_unit(end, "ns")) { return t; - } else if (!strncmp(end, "us", 2)) { + } else if (match_time_unit(end, "us")) { t *= 1000; return t; - } else if (!strncmp(end, "ms", 2)) { + } else if (match_time_unit(end, "ms")) { t *= 1000 * 1000; return t; - } else if (!strncmp(end, "s", 1)) { + } else if (match_time_unit(end, "s")) { t *= 1000 * 1000 * 1000; return t; } -- 2.53.0
