[PATCH v2] malloc: Do not clobber errno on __getrandom_nocancel (BZ#29624)

[Wilco Dijkstra]

Hi Adhemerval,

Another question, the syscall is defined as:

ssize_t getrandom (void *__buffer, size_t __length,

Doesn't this mean if we use 'int' for the return value, a large but valid syscall
result could be interpreted as a negative error value? It sounds like all code
processing the getrandom syscall should use ssize_t rather than int. Or do we
limit length to something fairly small?

 __arc4random_buf (void *p, size_t n)
 {
   static int seen_initialized;
-  size_t l;
+  int l;

Should be ssize_t?

+static inline int
+__getrandom_nocancel (void *buf, size_t buflen, unsigned int flags)

ssize_t?

+{
+  int save_errno = errno;
+  int r = __getrandom (buf, buflen, flags);

ssize_t?

+  r = r == -1 ? -errno : r;
+  __set_errno (save_errno);
+  return r;
+}
 
 #define __poll_infinity_nocancel(fds, nfds) \
   __poll (fds, nfds, -1)
diff --git a/sysdeps/unix/sysv/linux/not-cancel.h b/sysdeps/unix/sysv/linux/not-cancel.h
index a263d294b1..00ab75a405 100644
--- a/sysdeps/unix/sysv/linux/not-cancel.h
+++ b/sysdeps/unix/sysv/linux/not-cancel.h
@@ -71,7 +71,7 @@ __writev_nocancel_nostatus (int fd, const struct iovec *iov, int iovcnt)
 static inline int

ssize_t?

 __getrandom_nocancel (void *buf, size_t buflen, unsigned int flags)
 {
-  return INLINE_SYSCALL_CALL (getrandom, buf, buflen, flags);
+  return INTERNAL_SYSCALL_CALL (getrandom, buf, buflen, flags);
 }

Cheers,
Wilco