git: 1eb62930e736 - stable/14 - kern: zero out stack buffer after copying out random bits

The branch stable/14 has been updated by kevans:

URL: https://cgit.FreeBSD.org/src/commit/?id=1eb62930e73689ce8e9cc68cf6f5cdc337c56bf3

commit 1eb62930e73689ce8e9cc68cf6f5cdc337c56bf3
Author:     Kyle Evans <kevans@FreeBSD.org>
AuthorDate: 2024-07-15 20:17:47 +0000
Commit:     Kyle Evans <kevans@FreeBSD.org>
CommitDate: 2024-07-21 05:24:55 +0000

    kern: zero out stack buffer after copying out random bits
    
    The kern.arandom sysctl handler uses an intermediate buffer on the stack
    to hold random data that it subsequently copies out to the sysctl
    request.  Err on the side of caution and zero out the stack buffer after
    we're done with it to avoid a potential entropy leak later on.
    
    Reviewed by:    cem, emaste, markj
    
    (cherry picked from commit 5862c891bb7c588aa00538d85eb26ffe77d3f709)
---
 sys/kern/kern_mib.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sys/kern/kern_mib.c b/sys/kern/kern_mib.c
index 7d2a9e7f8474..8ce09a47ef58 100644
--- a/sys/kern/kern_mib.c
+++ b/sys/kern/kern_mib.c
@@ -182,10 +182,14 @@ sysctl_kern_arnd(SYSCTL_HANDLER_ARGS)
 {
 	char buf[256];
 	size_t len;
+	int error;
 
 	len = MIN(req->oldlen, sizeof(buf));
 	read_random(buf, len);
-	return (SYSCTL_OUT(req, buf, len));
+
+	error = SYSCTL_OUT(req, buf, len);
+	explicit_bzero(buf, len);
+	return (error);
 }
 
 SYSCTL_PROC(_kern, KERN_ARND, arandom,