From 105a72fd53c2fbfd9f66cf23f365b604f016772b Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Mon, 23 Jun 2025 15:16:01 -0500
Subject: [PATCH] Jesse Rosenstock pointed out that long masks would run past
 toybuf.

---
 tests/taskset.test   | 6 ++++++
 toys/other/taskset.c | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/tests/taskset.test b/tests/taskset.test
index 39bee16b..acd2869f 100755
--- a/tests/taskset.test
+++ b/tests/taskset.test
@@ -8,6 +8,7 @@ CPUS=$(($(nproc)+0))
 if [ $CPUS -lt 2 ]
 then
   echo "$SHOWSKIP: taskset (not SMP)"
+  return 2 > /dev/null
   exit
 fi
 MASK=$(printf %x $(((1<<CPUS)-1)))
@@ -31,3 +32,8 @@ testing 'run on first' \
 testing 'run on last' \
   'X=$(taskset $LAST cat /proc/self/stat); x() { echo ${39};}; x $X' \
   "$((CPUS-1))\n" '' ''
+
+testing "long mask doesn't segfault" \
+  'taskset $(printf %99999s | tr \  f) echo; echo $?' '\n0\n' '' ''
+testing "taskset error checking" \
+  'taskset 0 echo nope 2>/dev/null; echo $?' '1\n' '' ''
diff --git a/toys/other/taskset.c b/toys/other/taskset.c
index a3d0ffb3..cc33d94e 100644
--- a/toys/other/taskset.c
+++ b/toys/other/taskset.c
@@ -68,7 +68,7 @@ static void do_taskset(pid_t pid, int quiet)
 
     // Convert hex strong to mask[] bits
     memset(toybuf, 0, sizeof(toybuf));
-    k = strlen(s = *toys.optargs);
+    k = minof(strlen(s = *toys.optargs), 2*sizeof(toybuf));
     s += k;
     for (j = 0; j<k; j++) {
       unsigned long digit = *(--s) - '0';
-- 
2.39.5