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Tue, 18 Aug 2026 08:05:57 +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 ZWU/DGUShGrDfgAAD6G6ig (envelope-from ); Tue, 18 Aug 2026 08:05:57 +0000 Message-ID: <9f86fb45-8784-461e-9398-a0a930bea87c@suse.de> Date: Tue, 18 Aug 2026 10:05:27 +0200 Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH nf 1/1] netfilter: xt_IDLETIMER: validate label before debug logging in checkentry To: Ren Wei , netfilter-devel@vger.kernel.org Cc: pablo@netfilter.org, fw@strlen.de, phil@nwl.cc, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, luciano.coelho@nokia.com, kaber@trash.net, quic_manojbm@quicinc.com, quic_subashab@quicinc.com, vega@nebusec.ai, rakukuip@gmail.com References: Content-Language: en-US From: Fernando Fernandez Mancera In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.30 X-Spam-Level: X-Spam-Flag: NO X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_TWELVE(0.00)[16]; MID_RHS_MATCH_FROM(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[netfilter.org,strlen.de,nwl.cc,davemloft.net,google.com,kernel.org,redhat.com,nokia.com,trash.net,quicinc.com,nebusec.ai,gmail.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:email,suse.de:mid] On 8/18/26 3:56 AM, Ren Wei wrote: > From: Luxiao Xu > > Both idletimer_tg_checkentry() and idletimer_tg_checkentry_v1() invoke > pr_debug() with "%s" on info->label before idletimer_tg_helper() verifies > that the 28-byte label is properly NUL-terminated. > > If a user-supplied label is not NUL-terminated, printk format string > parsing reads past the end of the allocated target structure until it > encounters a zero byte. In builds with DEBUG enabled or when dynamic debug > is active for this callsite, this triggers a slab-out-of-bounds read > (detected by KASAN) and can disclose adjacent kernel memory into the logs. > > Fix this by moving the pr_debug() calls after idletimer_tg_helper() has > successfully validated the label string. > > Fixes: 0902b469bd25 ("netfilter: xtables: idletimer target implementation") > Fixes: 68983a354a65 ("netfilter: xtables: Add snapshot of hardidletimer target") > Cc: stable@vger.kernel.org > Reported-by: Vega > Assisted-by: Codex:gpt-5.4 > Signed-off-by: Luxiao Xu > Signed-off-by: Ren Wei > --- Reviewed-by: Fernando Fernandez Mancera Thanks!