From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Tue, 13 Jul 2010 13:21:52 +0000 Subject: [patch] net/sched: potential data corruption Message-Id: <20100713132152.GL5658@bicker> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jamal Hadi Salim Cc: "David S. Miller" , Stephen Hemminger , netdev@vger.kernel.org, kernel-janitors@vger.kernel.org, matthew@wil.cx The reset_policy() does: memset(d->tcfd_defdata, 0, SIMP_MAX_DATA); strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA); In the original code, the size of d->tcfd_defdata wasn't fixed and if strlen(defdata) was less than 31, reset_policy() would cause memory corruption. Please Note: The original alloc_defdata() assumes defdata is 32 characters and a NUL terminator while reset_policy() assumes defdata is 31 characters and a NUL. This patch updates alloc_defdata() to match reset_policy() (ie a shorter string). I'm not very familiar with this code so please review carefully. Signed-off-by: Dan Carpenter diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c index 1b4bc69..4a1d640 100644 --- a/net/sched/act_simple.c +++ b/net/sched/act_simple.c @@ -73,10 +73,10 @@ static int tcf_simp_release(struct tcf_defact *d, int bind) static int alloc_defdata(struct tcf_defact *d, char *defdata) { - d->tcfd_defdata = kstrndup(defdata, SIMP_MAX_DATA, GFP_KERNEL); + d->tcfd_defdata = kzalloc(SIMP_MAX_DATA, GFP_KERNEL); if (unlikely(!d->tcfd_defdata)) return -ENOMEM; - + strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA); return 0; }