From 9eed1bd59937e6828b00d2f2dfef631d964f3636 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Mon, 18 May 2026 10:43:07 -0400 Subject: [PATCH] scsi: fcoe: Reject FIP descriptors with zero fip_dlen in CVL walker drivers/scsi/fcoe/fcoe_ctlr.c::fcoe_ctlr_recv_clr_vlink() advanced the descriptor cursor by an attacker-supplied fip_dlen without ever requiring dlen >= sizeof(struct fip_desc) in the default branch. The named descriptor cases (FIP_DT_MAC, FIP_DT_NAME, FIP_DT_VN_ID) checked their per-type minimum lengths, but a FIP_DT_NON_CRITICAL descriptor (fip_dtype >= 128, which the standard requires receivers to silently ignore) skipped that check entirely. An unauthenticated L2 peer on the FCoE control VLAN could hang fcoe_ctlr_recv_work on an fcoe, qedf, or bnx2fc initiator indefinitely by emitting one FIP CVL frame whose single descriptor had fip_dtype == FIP_DT_NON_CRITICAL and fip_dlen == 0: the cursor advanced zero bytes per iteration and the loop condition rlen >= sizeof(*desc) stayed true forever, blocking every subsequent FIP frame on that controller. Tighten the outer dlen guard to also reject dlen < sizeof(struct fip_desc), so a malformed descriptor whose length cannot even cover the descriptor header is rejected before the switch. This is the same lower-bound the named cases already apply and is the minimum scope that closes the loop. Fixes: 97c8389d54b9 ("[SCSI] fcoe, libfcoe: Add support for FIP. FCoE discovery and keep-alive.") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Reviewed-by: Hannes Reinecke Link: https://patch.msgid.link/20260518144307.2820961-1-michael.bommarito@gmail.com Signed-off-by: Martin K. Petersen --- drivers/scsi/fcoe/fcoe_ctlr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c index 02cd4410efca..496ddd45f74d 100644 --- a/drivers/scsi/fcoe/fcoe_ctlr.c +++ b/drivers/scsi/fcoe/fcoe_ctlr.c @@ -1385,7 +1385,7 @@ static void fcoe_ctlr_recv_clr_vlink(struct fcoe_ctlr *fip, while (rlen >= sizeof(*desc)) { dlen = desc->fip_dlen * FIP_BPW; - if (dlen > rlen) + if (dlen < sizeof(*desc) || dlen > rlen) goto err; /* Drop CVL if there are duplicate critical descriptors */ if ((desc->fip_dtype < 32) &&