Description of problem:
If libcall read(sysfd, buffer, sizeof(buffer) returns 0, it may lead to an underflow later in buffer[len - 1].

...snip...
248 static unsigned int
249 get_flags(char *module)
250 {
251 char buffer[256], filename[256];
252 int sysfd, len;
253
254 snprintf(filename, 256, "/proc/sys/sunrpc/%s_debug", module);
255
256 if ((sysfd = open(filename, O_RDONLY)) < 0)

{ 257 perror(filename); 258 exit(1); 259 }

260 if ((len = read(sysfd, buffer, sizeof(buffer))) < 0)

{ // <- if len returns 0 here 261 perror("read"); 262 exit(1); 263 }

264 close(sysfd);
265 buffer[len - 1] = '\0'; // <- buffer underflow
266
267 return strtoul(buffer, NULL, 0);
268 }
...snip...

Version-Release number of selected component (if applicable):
nfs-utils-2.5.4-18.el9