From 032e084f0d43fda78c33abfc704ac13a0891a6e7 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Fri, 27 Feb 2026 18:43:09 +0000 Subject: [PATCH] tools/sched_ext: fix strtoul() misuse in scx_hotplug_seq() scx_hotplug_seq() uses strtoul() but validates the result with a negative check (val < 0), which can never be true for an unsigned return value. Use the endptr mechanism to verify the entire string was consumed, and check errno == ERANGE for overflow detection. Signed-off-by: David Carlier Signed-off-by: Tejun Heo --- tools/sched_ext/include/scx/compat.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/tools/sched_ext/include/scx/compat.h b/tools/sched_ext/include/scx/compat.h index 8b4897fc8b99..edccc99c7294 100644 --- a/tools/sched_ext/include/scx/compat.h +++ b/tools/sched_ext/include/scx/compat.h @@ -125,6 +125,7 @@ static inline long scx_hotplug_seq(void) { int fd; char buf[32]; + char *endptr; ssize_t len; long val; @@ -137,8 +138,10 @@ static inline long scx_hotplug_seq(void) buf[len] = 0; close(fd); - val = strtoul(buf, NULL, 10); - SCX_BUG_ON(val < 0, "invalid num hotplug events: %lu", val); + errno = 0; + val = strtoul(buf, &endptr, 10); + SCX_BUG_ON(errno == ERANGE || endptr == buf || + (*endptr != '\n' && *endptr != '\0'), "invalid num hotplug events: %ld", val); return val; }