utils: lockfile: avoid stack overflow for lockfile buffer

There appears to have been some change on openSUSE (likely some new hardening flags for builds, or some glibc hardening) such that incorrect buffer handling results in a segfault even if the buffer is never overflowed. Signed-off-by: Aleksa Sarai <[email protected]>
jesec · Jul 21, 2023 · 199e8f8 · 199e8f8
1 parent e9303f6
commit 199e8f8
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/src/utils/lockfile.cc b/src/utils/lockfile.cc
@@ -75,8 +75,9 @@ Lockfile::try_lock() {
   int  pos = ::gethostname(buf, 255);
 
   if (pos == 0) {
-    ::snprintf(buf + std::strlen(buf), 255, ":+%i\n", ::getpid());
-    ssize_t __attribute__((unused)) result = ::write(fd, buf, std::strlen(buf));
+    ssize_t len = std::strlen(buf);
+    ::snprintf(buf + len, 255 - len, ":+%i\n", ::getpid());
+    int __attribute__((unused)) result = ::write(fd, buf, std::strlen(buf));
   }
 
   ::close(fd);