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Date:      Sat, 16 May 2020 17:05:44 +0000 (UTC)
From:      Pawel Biernacki <kaktus@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r361113 - head/sys/net
Message-ID:  <202005161705.04GH5iWE053309@repo.freebsd.org>
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Author: kaktus
Date: Sat May 16 17:05:44 2020
New Revision: 361113
URL: https://svnweb.freebsd.org/changeset/base/361113

Log:
  sysctl: fix setting net.isr.dispatch during early boot
  
  Fix another collateral damage of r357614: netisr is initialised way before
  malloc() is available hence it can't use sysctl_handle_string() that
  allocates temporary buffer.  Handle that internally in
  sysctl_netisr_dispatch_policy().
  
  PR:		246114
  Reported by:	delphij
  Reviewed by:	kib
  Approved by:	kib (mentor)
  Differential Revision:	https://reviews.freebsd.org/D24858

Modified:
  head/sys/net/netisr.c

Modified: head/sys/net/netisr.c
==============================================================================
--- head/sys/net/netisr.c	Sat May 16 16:29:23 2020	(r361112)
+++ head/sys/net/netisr.c	Sat May 16 17:05:44 2020	(r361113)
@@ -345,19 +345,34 @@ static int
 sysctl_netisr_dispatch_policy(SYSCTL_HANDLER_ARGS)
 {
 	char tmp[NETISR_DISPATCH_POLICY_MAXSTR];
+	size_t len;
 	u_int dispatch_policy;
 	int error;
 
 	netisr_dispatch_policy_to_str(netisr_dispatch_policy, tmp,
 	    sizeof(tmp));
-	error = sysctl_handle_string(oidp, tmp, sizeof(tmp), req);
-	if (error == 0 && req->newptr != NULL) {
-		error = netisr_dispatch_policy_from_str(tmp,
-		    &dispatch_policy);
-		if (error == 0 && dispatch_policy == NETISR_DISPATCH_DEFAULT)
-			error = EINVAL;
-		if (error == 0)
-			netisr_dispatch_policy = dispatch_policy;
+	/*
+	 * netisr is initialised very early during the boot when malloc isn't
+	 * available yet so we can't use sysctl_handle_string() to process
+	 * any non-default value that was potentially set via loader.
+	 */
+	if (req->newptr != NULL) {
+		len = req->newlen - req->newidx;
+		if (len >= NETISR_DISPATCH_POLICY_MAXSTR)
+			return (EINVAL);
+		error = SYSCTL_IN(req, tmp, len);
+		if (error == 0) {
+			tmp[len] = '\0';
+			error = netisr_dispatch_policy_from_str(tmp,
+			    &dispatch_policy);
+			if (error == 0 &&
+			    dispatch_policy == NETISR_DISPATCH_DEFAULT)
+				error = EINVAL;
+			if (error == 0)
+				netisr_dispatch_policy = dispatch_policy;
+		}
+	} else {
+		error = sysctl_handle_string(oidp, tmp, sizeof(tmp), req);
 	}
 	return (error);
 }

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