From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793208954; b=WnDx998ndOkfeJceNvucoWlERS2qGBBvGptPRNF3C7LNNyYMh7MnIchJcJ0JXddg7waP 8nhnJIfHYXlBpwn/eEAC53uMWSfnp0Fzd5Fq1LkdsaiMbqi6rcgOsmyoVebxi82E+umwR atZBu7fx22NdzckRH14XuMihxvPGAJtPFpGnDtZb0T6FFne5HLDNpVo6GOsvMCiz6njhS 1Et0rzZkNcTusWYOMoTTqvUaZ1kMiHrwKiPA/8f7tQRcikpt8PDwx2cuyMI+QCbBUE+oV YqXlEHR6M8Add18kMw1kAFXxMOE0So9XW0diKSuivsvEsS1+YyKtAKFqBGFSpo13lfg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793208954; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=QbYehP/qLcCNkHhcPXkZ/cwg934/rOl38NsemsAfFmk=; b=boKoZo9zIYYjk5hD7qWoITKfrJKX3+fRqMeyiYQLIAgnNygvxvqgwVU/5q0au1TQyeG2 RCF+wR72rJEq7C78+8MhvngAkIsM83FF2GgAadS0sV8Si56Ldt2Fcz2zrfMVcyKmxsj8v phHg21VL+Ae6R8hH02g5xg2PpR9CeLBkeM+pXg6Yq2fau3aYsY6eFTRjcuBIIiLCaLZqN 0marFZRoNKR2ssHzZvAgik9zX4Q+OM2wIRJk0mWM29FskwKo/kn0LFJKXsCj8cJBWKeub 3oFFSa3DXcpr7qxgClmpXdjKjCrJOGAhq/0vr+q90Yw8ehMP6qgP3kbK879+/fx7kpg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=rfYPFcO0; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E0DE606A322; Wed, 28 Oct 2026 17:35:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=rfYPFcO0 Received: by smtp.kernel.org (Postfix) with ESMTPSA id F06051F01825; Wed, 28 Oct 2026 17:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793208954; bh=QbYehP/qLcCNkHhcPXkZ/cwg934/rOl38NsemsAfFmk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rfYPFcO0m5X2146KXrEDQnOMDME0BAoFaYpdIJWTDqT9//cm1qB+QbZUr4u9SJDSy YOFC27/yDmbslFR4EBAcTRGM1tPvafLLiK15DABpPYuMk0aSc8O7u6dqGNEmqvN9XM 3wW2fwtBKRKfi7bqm8PG6epPVqZ/aIPbdj6wtOc4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Stefan Fleischmann , Eric Dumazet , Michael Chan , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.10 301/516] bnxt_en: fix DMA mapping length for padded small packets Date: Wed, 28 Oct 2026 17:57:33 +0100 Message-ID: <20261028170010.622196521@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170003.522232767@linuxfoundation.org> References: <20261028170003.522232767@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit a51d233ccd4889aadb71dace863525cc2b00271e ] Stefan Fleischmann reported Intel IOMMU DMA Read faults on BCM57412 NetXtreme-E NICs when transmitting packets on VLAN/macvlan interfaces: DMAR: [DMA Read NO_PASID] Request device [18:00.0] fault addr 0xfc499000 [fault reason 0x06] PTE Read access is not set bnxt_en 0000:18:00.0 eno1np0: Abandoning msg {0xb4 0x41a} len: 0 due to firmware status: 0x2000001 ... NETDEV WATCHDOG: eno1np0 (bnxt_en): transmit queue 0 timed out The fault address (0xfc499000) is on an exact 4KB page boundary, pointing to a DMA read buffer overrun. In bnxt_start_xmit(), packets smaller than BNXT_MIN_PKT_SIZE (52 bytes), such as 42-byte untagged ARP frames, are padded: if (length < BNXT_MIN_PKT_SIZE) { pad = BNXT_MIN_PKT_SIZE - length; if (skb_pad(skb, pad)) goto tx_kick_pending; length = BNXT_MIN_PKT_SIZE; } mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE); ... dma_unmap_len_set(tx_buf, len, len); However, 'len' was initialized earlier to skb_headlen(skb) (e.g. 42 bytes) and is left unadjusted after padding. Consequently, dma_map_single() and dma_unmap_len_set() map and track only 42 bytes. Later, the hardware TX buffer descriptor is programmed with the padded length: txbd->tx_bd_len_flags_type = cpu_to_le32(((len + pad) << TX_BD_LEN_SHIFT) | flags | TX_BD_FLAGS_PACKET_END); The NIC DMA engine is thus instructed to read 52 bytes from a region where only 42 bytes were DMA-mapped. If skb->data ends near the boundary of a 4KB page (within 'pad' bytes of the next page), the hardware DMA read overruns into the unmapped adjacent page, triggering an IOMMU fault. This issue was exposed after commit 447cbe95ebb9 ("vlan: fix skb_under_panic and races when toggling HW VLAN offload") because reserving extra VLAN headroom rounded LL_RESERVED_SPACE from 48 up to 64 bytes, shifting skb->data offsets and potentially causing small frames to land right against page boundaries. Fix this by using skb_put_padto(skb, BNXT_MIN_PKT_SIZE) in bnxt_start_xmit(), before skb_shinfo(skb)->nr_frags is sampled, because padding might linearize the skb. This ensures skb->len and skb_headlen(skb) reflect the padded size so that dma_map_single() maps the full buffer and the descriptor length is consistent. This also removes the temporary 'pad' variable and masking logic. The padding is done after the SW USO branch, otherwise bnxt_sw_udp_gso_xmit() would account the padding as UDP payload and send it in extra segments. Note that SW USO segments are still not padded: with IPv4, a segment carrying less than 10 bytes of UDP payload (small gso_size, or a short last segment) is sent as a frame shorter than BNXT_MIN_PKT_SIZE. This is a separate issue, left for a followup patch. Fixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.") Cc: stable@vger.kernel.org Reported-by: Stefan Fleischmann Closes: https://lore.kernel.org/netdev/20261004122616.56714cbd@nargothrond/ Signed-off-by: Eric Dumazet Reviewed-by: Michael Chan Link: https://patch.msgid.link/20261007051747.455273-1-edumazet@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c index ee849e49f3731..3281eb09f79ed 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c @@ -429,7 +429,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) struct netdev_queue *txq; int i; dma_addr_t mapping; - unsigned int length, pad = 0; + unsigned int length; u32 len, free_size, vlan_tag_flags, cfa_action, flags; u16 prod, last_frag; struct pci_dev *pdev = bp->pdev; @@ -447,6 +447,14 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) txr = &bp->tx_ring[bp->tx_ring_map[i]]; prod = txr->tx_prod; + /* Must be done before skb_shinfo(skb)->nr_frags is sampled, + * because skb_put_padto() might linearize the skb. + */ + if (skb_put_padto(skb, BNXT_MIN_PKT_SIZE)) { + /* SKB already freed. */ + goto tx_kick_pending; + } + free_size = bnxt_tx_avail(bp, txr); if (unlikely(free_size < skb_shinfo(skb)->nr_frags + 2)) { /* We must have raced with NAPI cleanup */ @@ -554,14 +562,6 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) } normal_tx: - if (length < BNXT_MIN_PKT_SIZE) { - pad = BNXT_MIN_PKT_SIZE - length; - if (skb_pad(skb, pad)) - /* SKB already freed. */ - goto tx_kick_pending; - length = BNXT_MIN_PKT_SIZE; - } - mapping = dma_map_single(&pdev->dev, skb->data, len, DMA_TO_DEVICE); if (unlikely(dma_mapping_error(&pdev->dev, mapping))) @@ -636,10 +636,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) txbd->tx_bd_len_flags_type = cpu_to_le32(flags); } - flags &= ~TX_BD_LEN; - txbd->tx_bd_len_flags_type = - cpu_to_le32(((len + pad) << TX_BD_LEN_SHIFT) | flags | - TX_BD_FLAGS_PACKET_END); + txbd->tx_bd_len_flags_type |= cpu_to_le32(TX_BD_FLAGS_PACKET_END); netdev_tx_sent_queue(txq, skb->len); -- 2.53.0