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Tue, 10 Nov 2026 07:21:40 +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 pdnABwTG8mppagAAD6G6ig (envelope-from ); Tue, 10 Nov 2026 07:21:40 +0000 Message-ID: Date: Tue, 10 Nov 2026 08:21:39 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] nvme-auth: use the parsed offset for the DH-CHAP key To: shao.mingyin@zte.com.cn, kbusch@kernel.org, axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, linux-nvme@lists.infradead.org Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261109225919740-DfVem3ttLxIAe7wl3Puh@zte.com.cn> Content-Language: en-US From: Hannes Reinecke In-Reply-To: <20261109225919740-DfVem3ttLxIAe7wl3Puh@zte.com.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-13.29 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-0.998]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[8]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_NONE(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:email] X-Spam-Score: -13.29 X-Spam-Level: X-Spam-Flag: NO On 11/9/26 3:59 PM, shao.mingyin@zte.com.cn wrote: > From: Shao Mingyin > > nvme_auth_parse_key() accepts the DH-HMAC-CHAP key with > > if (sscanf(secret, "DHHC-1:%hhd:%*s:", &key_hash) != 1) > return -EINVAL; > > and then skips a hardcoded ten characters: > > key = nvme_auth_extract_key(secret + 10, key_hash); > > The ten characters assume that the hash identifier is exactly two > characters long. A string such as "DHHC-1:1:" still makes sscanf() > return 1, and secret + 10 then points one byte past the NUL terminator > of the buffer. nvme_auth_extract_key() starts with > strlen(secret), so it reads past the end of the allocation. The sysfs > dhchap_secret and dhchap_ctrl_secret stores only require seven > characters and a "DHHC-1:" prefix, so a short value reaches this code > (even though the nvme-fabrics option parser rejects secrets shorter than > eleven characters). > > Use the %n conversion to obtain the real offset after the > "DHHC-1::" prefix and reject a string where the prefix is not > complete. This accepts both one and two character hash identifiers and > never starts the key past the terminator. > > Fixes: f50fff73d620 ("nvme: implement In-Band authentication") > Cc: stable@vger.kernel.org > Signed-off-by: Shao Mingyin > --- > Tested on 7.3.0-next-20261030 (QEMU/TCG guest, KASAN) with a live loop > controller and host DH-CHAP. > > Writing the 9-byte secret "DHHC-1:1:" to the dhchap_secret sysfs > attribute makes the driver start the key ten bytes in, one byte past > the NUL terminator: > > unpatched patched > KASAN slab-out-of-bounds in write rejected (-EINVAL) > strlen/strrchr, nvme_auth_extract_key > > diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c > index e2e0c736540a..1fdc4e4ed0b9 100644 > --- a/drivers/nvme/common/auth.c > +++ b/drivers/nvme/common/auth.c > @@ -489,17 +489,19 @@ int nvme_auth_parse_key(const char *secret, struct nvme_dhchap_key **ret_key) > { > struct nvme_dhchap_key *key; > u8 key_hash; > + int offset = 0; > > if (!secret) { > *ret_key = NULL; > return 0; > } > > - if (sscanf(secret, "DHHC-1:%hhd:%*s:", &key_hash) != 1) > + if (sscanf(secret, "DHHC-1:%hhd:%n", &key_hash, &offset) != 1 || > + !offset) > return -EINVAL; > > /* Pass in the secret without the 'DHHC-1:XX:' prefix */ > - key = nvme_auth_extract_key(secret + 10, key_hash); > + key = nvme_auth_extract_key(secret + offset, key_hash); > if (IS_ERR(key)) { > *ret_key = NULL; > return PTR_ERR(key); An easier fix would've been to check that the string is longer than 10 bytes. But anyway. Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich