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[204.195.123.141]) by smtp.gmail.com with ESMTPSA id oh6-20020a17090b3a4600b0028cc9afaae9sm4961227pjb.34.2024.01.12.17.46.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jan 2024 17:46:52 -0800 (PST) Date: Fri, 12 Jan 2024 17:46:50 -0800 From: Stephen Hemminger To: Maks Mishin Cc: netdev@vger.kernel.org Subject: Re: [PATCH] ifstat: Add NULL pointer check for argument of strdup() Message-ID: <20240112174650.6216eccd@hermes.local> In-Reply-To: <20240110205252.20870-1-maks.mishinFZ@gmail.com> References: <20240110205252.20870-1-maks.mishinFZ@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 10 Jan 2024 23:52:52 +0300 Maks Mishin wrote: > When calling a strdup() function its argument do not being checked > for NULL pointer. > Added NULL pointer checks in body of get_nlmsg_extended(), get_nlmsg() and > load_raw_data() functions. > > Signed-off-by: Maks Mishin Yes, ifstat has lots of poor memory management, but this patch isn't addressing it. > --- > misc/ifstat.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/misc/ifstat.c b/misc/ifstat.c > index f6f9ba50..ee301799 100644 > --- a/misc/ifstat.c > +++ b/misc/ifstat.c > @@ -129,7 +129,12 @@ static int get_nlmsg_extended(struct nlmsghdr *m, void *arg) > abort(); > > n->ifindex = ifsm->ifindex; > - n->name = strdup(ll_index_to_name(ifsm->ifindex)); > + const char *name = ll_index_to_name(ifsm->ifindex); > + > + if (name == NULL) > + return -1; > + > + n->name = strdup(name); > What if strdup() returns NULL? The error handling in ifstat is frankly aweful. It just calls abort() everywhere. > if (sub_type == NO_SUB_TYPE) { > memcpy(&n->val, RTA_DATA(tb[filter_type]), sizeof(n->val)); > @@ -175,7 +180,12 @@ static int get_nlmsg(struct nlmsghdr *m, void *arg) > if (!n) > abort(); > n->ifindex = ifi->ifi_index; > - n->name = strdup(RTA_DATA(tb[IFLA_IFNAME])); > + const char *name = RTA_DATA(tb[IFLA_IFNAME]); > + > + if (name == NULL) > + return -1; This NULL check can't happen. A few lines above, there is check for tb[IFLA_IFNAME] being NULL, and RTA_DATA() is macro that just offsets that netlink attribute to find the data. > + > + n->name = strdup(name); > memcpy(&n->ival, RTA_DATA(tb[IFLA_STATS]), sizeof(n->ival)); > memset(&n->rate, 0, sizeof(n->rate)); > for (i = 0; i < MAXS; i++) > @@ -263,6 +273,9 @@ static void load_raw_table(FILE *fp) > abort(); > *next++ = 0; > > + if (p == NULL) > + abort(); > + > n->name = strdup(p); > p = next; >