getservbyport_r: fix out-of-bounds buffer read

[musl] / src / unistd / nice.c

diff --git a/src/unistd/nice.c b/src/unistd/nice.c
index da56996..1c2295f 100644 (file)
--- a/src/unistd/nice.c
+++ b/src/unistd/nice.c
@@ -1,12 +1,23 @@
 #include <unistd.h>
+#include <errno.h>
 #include <sys/resource.h>
+#include <limits.h>
 #include "syscall.h"
 
 int nice(int inc)
 {
-#ifdef SYS_nice
-       return syscall(SYS_nice, inc);
-#else
-       return setpriority(PRIO_PROCESS, 0, getpriority(PRIO_PROCESS, 0)+inc);
-#endif
+       int prio = inc;
+       // Only query old priority if it can affect the result.
+       // This also avoids issues with integer overflow.
+       if (inc > -2*NZERO && inc < 2*NZERO)
+               prio += getpriority(PRIO_PROCESS, 0);
+       if (prio > NZERO-1) prio = NZERO-1;
+       if (prio < -NZERO) prio = -NZERO;
+       if (setpriority(PRIO_PROCESS, 0, prio)) {
+               if (errno == EACCES)
+                       errno = EPERM;
+               return -1;
+       } else {
+               return prio;
+       }
 }