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Thu, 21 Mar 2024 12:52:11 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Ib5vIXst/GXVTgAAD6G6ig (envelope-from ); Thu, 21 Mar 2024 12:52:11 +0000 Message-ID: Date: Thu, 21 Mar 2024 15:52:10 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] flow_dissector: prevent NULL pointer dereference in __skb_flow_dissect Content-Language: en-US To: Anastasia Belova , "David S. Miller" Cc: Eric Dumazet , Jakub Kicinski , Jiri Pirko , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org References: <20240321123446.7012-1-abelova@astralinux.ru> From: Denis Kirjanov In-Reply-To: <20240321123446.7012-1-abelova@astralinux.ru> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Level: Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=eoVNRrd4; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=LFpWYcGw X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-2.50 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; XM_UA_NO_VERSION(0.01)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BAYES_HAM(-0.00)[41.68%]; MIME_GOOD(-0.10)[text/plain]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; NEURAL_HAM_LONG(-1.00)[-1.000]; DWL_DNSWL_LOW(-1.00)[suse.de:dkim]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[8]; DBL_BLOCKED_OPENRESOLVER(0.00)[astralinux.ru:email,suse.de:dkim,linuxtesting.org:url]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] X-Spam-Score: -2.50 X-Rspamd-Queue-Id: 68B5A373B8 X-Spam-Flag: NO On 3/21/24 15:34, Anastasia Belova wrote: > skb is an optional parameter, so it may be NULL. > Add check defore dereference in eth_hdr. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > Fixes: 690e36e726d0 ("net: Allow raw buffers to be passed into the flow dissector.") > Signed-off-by: Anastasia Belova As request in the previous email please show the actual data flow that leads to a null pointer dereference. Also please read function description: ... * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified ... > --- > net/core/flow_dissector.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c > index 272f09251343..68a8228ffae3 100644 > --- a/net/core/flow_dissector.c > +++ b/net/core/flow_dissector.c > @@ -1139,6 +1139,8 @@ bool __skb_flow_dissect(const struct net *net, > > if (dissector_uses_key(flow_dissector, > FLOW_DISSECTOR_KEY_ETH_ADDRS)) { > + if (!skb) > + goto out_bad; > struct ethhdr *eth = eth_hdr(skb); > struct flow_dissector_key_eth_addrs *key_eth_addrs; >