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Miller" , Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , Eric Dumazet Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <15eba3b2-80e2-5547-8ad9-167d810ad7e3@virtuozzo.com> From: Julian Wiedmann Message-ID: Date: Thu, 5 Aug 2021 14:55:50 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: rwo93foxGXxQ0O3DAyRi6fGT9gb2c79H X-Proofpoint-ORIG-GUID: dhmrbn5khhUnSVVXn9MjsMc6OioutPoZ X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-05_04:2021-08-05,2021-08-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 mlxlogscore=952 spamscore=0 malwarescore=0 phishscore=0 lowpriorityscore=0 mlxscore=0 impostorscore=0 adultscore=0 priorityscore=1501 clxscore=1011 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108050069 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 02.08.21 11:52, Vasily Averin wrote: > Unlike skb_realloc_headroom, new helper skb_expand_head > does not allocate a new skb if possible. > > Signed-off-by: Vasily Averin > --- > drivers/net/vrf.c | 21 +++++++-------------- > 1 file changed, 7 insertions(+), 14 deletions(-) > [...] > /* Be paranoid, rather than too clever. */ > if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { > - struct sk_buff *skb2; > - > - skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); > - if (!skb2) { > - ret = -ENOMEM; > - goto err; > + skb = skb_expand_head(skb, hh_len); > + if (!skb) { > + skb->dev->stats.tx_errors++; > + return -ENOMEM; Hello Vasily, FYI, Coverity complains that we check skb != NULL here but then still dereference skb->dev: *** CID 1506214: Null pointer dereferences (FORWARD_NULL) /drivers/net/vrf.c: 867 in vrf_finish_output() 861 nf_reset_ct(skb); 862 863 /* Be paranoid, rather than too clever. */ 864 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 865 skb = skb_expand_head(skb, hh_len); 866 if (!skb) { >>> CID 1506214: Null pointer dereferences (FORWARD_NULL) >>> Dereferencing null pointer "skb". 867 skb->dev->stats.tx_errors++; 868 return -ENOMEM; 869 } 870 } 871 872 rcu_read_lock_bh();