From: Pauli <paul.dale@oracle.com>
Date: Sat, 24 Aug 2019 06:13:24 +0000 (+1000)
Subject: Avoid overflowing FDSET when using select(2).
X-Git-Tag: openssl-3.0.0-alpha1~1548
X-Git-Url: http://git.ipfire.org/?p=thirdparty%2Fopenssl.git;a=commitdiff_plain;h=e1f8584d47a499301fba781086af6885fcf21fec

Avoid overflowing FDSET when using select(2).

There is a problem in the rand_unix.c code when the random seed fd is greater
than or equal to FD_SETSIZE and the FDSET overruns its limit and walks the
stack.

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/9686)
---

diff --git a/crypto/rand/rand_unix.c b/crypto/rand/rand_unix.c
index 0ca66e41ff..7e20fa29c6 100644
--- a/crypto/rand/rand_unix.c
+++ b/crypto/rand/rand_unix.c
@@ -390,7 +390,7 @@ static int wait_random_seeded(void)
             }
             /* Open /dev/random and wait for it to be readable */
             if ((fd = open(DEVRANDOM_WAIT, O_RDONLY)) != -1) {
-                if (DEVRANDM_WAIT_USE_SELECT) {
+                if (DEVRANDM_WAIT_USE_SELECT && fd < FD_SETSIZE) {
                     FD_ZERO(&fds);
                     FD_SET(fd, &fds);
                     while ((r = select(fd + 1, &fds, NULL, NULL, NULL)) < 0