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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45d9ec39ff1sm58513115f8f.10.2026.05.20.05.58.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2026 05:58:50 -0700 (PDT) Date: Wed, 20 May 2026 13:58:48 +0100 From: David Laight To: Michael Bommarito Cc: "Martin K. Petersen" , "James E.J. Bottomley" , Nilesh Javali , Himanshu Madhani , Shyam Sundar , James Smart , Hannes Reinecke , John Meneghini , Bryan Gurney , Justin Tee , Christoph Hellwig , Keith Busch , Kees Cook , linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3] scsi: scsi_transport_fc: widen FPIN pname walker counter to u32 Message-ID: <20260520135848.6df9f7d2@pumpkin> In-Reply-To: <20260519190615.2761667-1-michael.bommarito@gmail.com> References: <20260518143706.2808177-1-michael.bommarito@gmail.com> <20260519190615.2761667-1-michael.bommarito@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@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 Tue, 19 May 2026 15:06:15 -0400 Michael Bommarito wrote: > An adjacent Fibre Channel fabric actor that can deliver an FPIN ELS > frame to an lpfc or qla2xxx Linux initiator can trigger a non-return > in the generic FC transport. This is not a local userspace or IP > network path; the attacker must be able to inject fabric traffic, for > example as a compromised switch or fabric controller, or as a same-zone > N_Port on a fabric that permits source spoofing. > > The Link-Integrity and Peer-Congestion FPIN walkers used a u8 loop > counter against the 32-bit on-wire pname_count field, and did not bound > pname_count by the descriptor body already validated by the TLV walker. > A pname_count of 256 therefore wraps the counter and keeps the loop > condition true indefinitely. > > Factor the shared pname_list[] walk into one helper, widen the counter > to u32, and clamp pname_count against the entries that fit in the > descriptor body before iterating. > > Fixes: 3dcfe0de5a97 ("scsi: fc: Parse FPIN packets and update statistics") > Cc: stable@vger.kernel.org > Assisted-by: Claude:claude-opus-4-7 > Signed-off-by: Michael Bommarito > --- > Changes in v3: > - State the fabric-adjacent threat model explicitly in the commit > message and clarify that this is not local userspace or IP-network > reachable. > - Use min_t(u32, ...) for the pname_count clamp, as Christoph suggested. > - Use FC_TLV_DESC_LENGTH_FROM_SZ() instead of open-coding the descriptor > body length calculation. > - Factor the duplicate LI and peer-congestion pname walker into a common > helper while preserving the LI-only host-stat update. > > Changes in v2: > - Drop the redundant cover letter shipped with v1. A single-patch send > does not need one, and the v1 cover carried stale draft markers. > > drivers/scsi/scsi_transport_fc.c | 77 +++++++++++++++++--------------- > 1 file changed, 41 insertions(+), 36 deletions(-) > > diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c > index dce95e361daf0..0684d8c69c3c6 100644 > --- a/drivers/scsi/scsi_transport_fc.c > +++ b/drivers/scsi/scsi_transport_fc.c > @@ -737,6 +737,37 @@ fc_cn_stats_update(u16 event_type, struct fc_fpin_stats *stats) > } > } > > +static void > +fc_fpin_pname_stats_update(struct Scsi_Host *shost, > + struct fc_rport *attach_rport, u16 event_type, > + u32 desc_len, u32 fixed_len, u32 pname_count, > + __be64 *pname_list, > + void (*stats_update)(u16 event_type, > + struct fc_fpin_stats *stats)) > +{ > + u32 i, max_count; > + struct fc_rport *rport; > + u64 wwpn; > + > + if (desc_len < fixed_len) > + max_count = 0; > + else > + max_count = (desc_len - fixed_len) / sizeof(pname_list[0]); > + pname_count = min_t(u32, pname_count, max_count); No min_t() please, everything is unsigned so min() in fine. The above might even more readable without the extra variable: if (desc_len < fixed_len) pname_count = min(pname_count, (desc_len - fixed_len) / sizeof(pname_list[0])); If you think the line is too long s/pname_count/count/g -- David > + > + for (i = 0; i < pname_count; i++) { > + wwpn = be64_to_cpu(pname_list[i]); > + rport = fc_find_rport_by_wwpn(shost, wwpn); > + if (rport && > + (rport->roles & FC_PORT_ROLE_FCP_TARGET || > + rport->roles & FC_PORT_ROLE_NVME_TARGET)) { > + if (rport == attach_rport) > + continue; > + stats_update(event_type, &rport->fpin_stats); > + } > + } > +} > + > /* > * fc_fpin_li_stats_update - routine to update Link Integrity > * event statistics. > @@ -747,13 +778,11 @@ fc_cn_stats_update(u16 event_type, struct fc_fpin_stats *stats) > static void > fc_fpin_li_stats_update(struct Scsi_Host *shost, struct fc_tlv_desc *tlv) > { > - u8 i; > struct fc_rport *rport = NULL; > struct fc_rport *attach_rport = NULL; > struct fc_host_attrs *fc_host = shost_to_fc_host(shost); > struct fc_fn_li_desc *li_desc = (struct fc_fn_li_desc *)tlv; > u16 event_type = be16_to_cpu(li_desc->event_type); > - u64 wwpn; > > rport = fc_find_rport_by_wwpn(shost, > be64_to_cpu(li_desc->attached_wwpn)); > @@ -764,22 +793,11 @@ fc_fpin_li_stats_update(struct Scsi_Host *shost, struct fc_tlv_desc *tlv) > fc_li_stats_update(event_type, &attach_rport->fpin_stats); > } > > - if (be32_to_cpu(li_desc->pname_count) > 0) { > - for (i = 0; > - i < be32_to_cpu(li_desc->pname_count); > - i++) { > - wwpn = be64_to_cpu(li_desc->pname_list[i]); > - rport = fc_find_rport_by_wwpn(shost, wwpn); > - if (rport && > - (rport->roles & FC_PORT_ROLE_FCP_TARGET || > - rport->roles & FC_PORT_ROLE_NVME_TARGET)) { > - if (rport == attach_rport) > - continue; > - fc_li_stats_update(event_type, > - &rport->fpin_stats); > - } > - } > - } > + fc_fpin_pname_stats_update(shost, attach_rport, event_type, > + be32_to_cpu(li_desc->desc_len), > + FC_TLV_DESC_LENGTH_FROM_SZ(*li_desc), > + be32_to_cpu(li_desc->pname_count), > + li_desc->pname_list, fc_li_stats_update); > > if (fc_host->port_name == be64_to_cpu(li_desc->attached_wwpn)) > fc_li_stats_update(event_type, &fc_host->fpin_stats); > @@ -827,13 +845,11 @@ static void > fc_fpin_peer_congn_stats_update(struct Scsi_Host *shost, > struct fc_tlv_desc *tlv) > { > - u8 i; > struct fc_rport *rport = NULL; > struct fc_rport *attach_rport = NULL; > struct fc_fn_peer_congn_desc *pc_desc = > (struct fc_fn_peer_congn_desc *)tlv; > u16 event_type = be16_to_cpu(pc_desc->event_type); > - u64 wwpn; > > rport = fc_find_rport_by_wwpn(shost, > be64_to_cpu(pc_desc->attached_wwpn)); > @@ -844,22 +860,11 @@ fc_fpin_peer_congn_stats_update(struct Scsi_Host *shost, > fc_cn_stats_update(event_type, &attach_rport->fpin_stats); > } > > - if (be32_to_cpu(pc_desc->pname_count) > 0) { > - for (i = 0; > - i < be32_to_cpu(pc_desc->pname_count); > - i++) { > - wwpn = be64_to_cpu(pc_desc->pname_list[i]); > - rport = fc_find_rport_by_wwpn(shost, wwpn); > - if (rport && > - (rport->roles & FC_PORT_ROLE_FCP_TARGET || > - rport->roles & FC_PORT_ROLE_NVME_TARGET)) { > - if (rport == attach_rport) > - continue; > - fc_cn_stats_update(event_type, > - &rport->fpin_stats); > - } > - } > - } > + fc_fpin_pname_stats_update(shost, attach_rport, event_type, > + be32_to_cpu(pc_desc->desc_len), > + FC_TLV_DESC_LENGTH_FROM_SZ(*pc_desc), > + be32_to_cpu(pc_desc->pname_count), > + pc_desc->pname_list, fc_cn_stats_update); > } > > /*