getservbyport_r: fix out-of-bounds buffer read

[musl] / src / unistd / getcwd.c

diff --git a/src/unistd/getcwd.c b/src/unistd/getcwd.c
index 2e540cd..f407ffe 100644 (file)
--- a/src/unistd/getcwd.c
+++ b/src/unistd/getcwd.c
@@ -6,8 +6,20 @@
 
 char *getcwd(char *buf, size_t size)
 {
-       char tmp[PATH_MAX];
-       if (!buf) buf = tmp, size = PATH_MAX;
-       if (syscall(SYS_getcwd, buf, size) < 0) return 0;
+       char tmp[buf ? 1 : PATH_MAX];
+       if (!buf) {
+               buf = tmp;
+               size = sizeof tmp;
+       } else if (!size) {
+               errno = EINVAL;
+               return 0;
+       }
+       long ret = syscall(SYS_getcwd, buf, size);
+       if (ret < 0)
+               return 0;
+       if (ret == 0 || buf[0] != '/') {
+               errno = ENOENT;
+               return 0;
+       }
        return buf == tmp ? strdup(buf) : buf;
 }