linux-kernel - [PATCH 4.14 50/53] netfilter: nf_log: dont hold nf_log

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180710182501.602555951@linuxfoundation.org>
Date:   Tue, 10 Jul 2018 20:25:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jann Horn <jannh@...gle.com>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH 4.14 50/53] netfilter: nf_log: dont hold nf_log_mutex during user access

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jann Horn <jannh@...gle.com>

commit ce00bf07cc95a57cd20b208e02b3c2604e532ae8 upstream.

The old code would indefinitely block other users of nf_log_mutex if
a userspace access in proc_dostring() blocked e.g. due to a userfaultfd
region. Fix it by moving proc_dostring() out of the locked region.

This is a followup to commit 266d07cb1c9a ("netfilter: nf_log: fix
sleeping function called from invalid context"), which changed this code
from using rcu_read_lock() to taking nf_log_mutex.

Fixes: 266d07cb1c9a ("netfilter: nf_log: fix sleeping function calle[...]")
Signed-off-by: Jann Horn <jannh@...gle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/netfilter/nf_log.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -458,14 +458,17 @@ static int nf_log_proc_dostring(struct c
 		rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
 		mutex_unlock(&nf_log_mutex);
 	} else {
+		struct ctl_table tmp = *table;
+
+		tmp.data = buf;
 		mutex_lock(&nf_log_mutex);
 		logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
 		if (!logger)
-			table->data = "NONE";
+			strlcpy(buf, "NONE", sizeof(buf));
 		else
-			table->data = logger->name;
-		r = proc_dostring(table, write, buffer, lenp, ppos);
+			strlcpy(buf, logger->name, sizeof(buf));
 		mutex_unlock(&nf_log_mutex);
+		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
 	}
 
 	return r;