From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 4/6] netfilter: nf_log: fix uninit read in nf_log_proc_dostring Date: Wed, 27 Jun 2018 17:22:21 +0200 Message-ID: <20180627152223.3633-5-pablo@netfilter.org> References: <20180627152223.3633-1-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: In-Reply-To: <20180627152223.3633-1-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org From: Jann Horn When proc_dostring() is called with a non-zero offset in strict mode, it doesn't just write to the ->data buffer, it also reads. Make sure it doesn't read uninitialized data. Fixes: c6ac37d8d884 ("netfilter: nf_log: fix error on write NONE to [...]") Signed-off-by: Jann Horn Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_log.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c index 426457047578..2c47f9ec3511 100644 --- a/net/netfilter/nf_log.c +++ b/net/netfilter/nf_log.c @@ -424,6 +424,10 @@ static int nf_log_proc_dostring(struct ctl_table *table, int write, if (write) { struct ctl_table tmp = *table; + /* proc_dostring() can append to existing strings, so we need to + * initialize it as an empty string. + */ + buf[0] = '\0'; tmp.data = buf; r = proc_dostring(&tmp, write, buffer, lenp, ppos); if (r) -- 2.11.0