From: Wei Fang Date: Wed, 20 May 2026 06:44:16 +0000 (+0800) Subject: net: enetc: fix TOCTOU race and validate VF MAC address X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c666fa632fe628c34904bcd59aeb96bf08e40d31;p=thirdparty%2Fkernel%2Flinux.git net: enetc: fix TOCTOU race and validate VF MAC address Sashiko reported that the PF driver accepts arbitrary MAC address from from VF mailbox messages without proper validation, creating a security vulnerability [1]. In enetc_msg_pf_set_vf_primary_mac_addr(), the MAC address is extracted directly from the message buffer (cmd->mac.sa_data) and programmed into hardware via pf->ops->set_si_primary_mac() without any validity checks. A malicious VF can configure a multicast, broadcast, or all-zero MAC address. Therefore, a validation to check the MAC address provided by VF is required. However, simply checking the MAC address is not enough, because it also has the potential TOCTOU race [2]: The code reads the MAC address from the DMA buffer to validate it via is_valid_ether_addr(), if validation passes, reads the same DMA buffer a second time when calling enetc_pf_set_primary_mac_addr() to program the hardware. A malicious VF can exploit this window by overwriting the MAC address in the DMA buffer between the validation check and the hardware programming, bypassing the validation entirely. Therefore, allocate a local buffer in enetc_msg_handle_rxmsg() and copy the message content from the DMA buffer via memcpy() before processing. This ensures the PF operates on a stable snapshot that the VF cannot modify. Link: https://sashiko.dev/#/patchset/20260511080805.2052495-1-wei.fang%40nxp.com #1 Link: https://sashiko.dev/#/patchset/20260513103021.2190593-1-wei.fang%40nxp.com #2 Fixes: beb74ac878c8 ("enetc: Add vf to pf messaging support") Signed-off-by: Wei Fang Reviewed-by: Harshitha Ramamurthy Link: https://patch.msgid.link/20260520064421.91569-5-wei.fang@nxp.com Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.c b/drivers/net/ethernet/freescale/enetc/enetc_pf.c index dea3a92c4722..09c642040892 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc_pf.c +++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.c @@ -478,21 +478,24 @@ static void enetc_configure_port(struct enetc_pf *pf) /* Messaging */ static u16 enetc_msg_pf_set_vf_primary_mac_addr(struct enetc_pf *pf, - int vf_id) + int vf_id, void *msg) { struct enetc_vf_state *vf_state = &pf->vf_state[vf_id]; - struct enetc_msg_swbd *msg = &pf->rxmsg[vf_id]; - struct enetc_msg_cmd_set_primary_mac *cmd; + struct enetc_msg_cmd_set_primary_mac *cmd = msg; struct device *dev = &pf->si->pdev->dev; - u16 cmd_id; + u16 cmd_id = cmd->header.id; char *addr; - cmd = (struct enetc_msg_cmd_set_primary_mac *)msg->vaddr; - cmd_id = cmd->header.id; if (cmd_id != ENETC_MSG_CMD_MNG_ADD) return ENETC_MSG_CMD_STATUS_FAIL; addr = cmd->mac.sa_data; + if (!is_valid_ether_addr(addr)) { + dev_err_ratelimited(dev, "VF%d attempted to set invalid MAC\n", + vf_id); + return ENETC_MSG_CMD_STATUS_FAIL; + } + if (vf_state->flags & ENETC_VF_FLAG_PF_SET_MAC) { dev_err_ratelimited(dev, "VF%d attempted to override PF set MAC\n", @@ -507,17 +510,33 @@ static u16 enetc_msg_pf_set_vf_primary_mac_addr(struct enetc_pf *pf, void enetc_msg_handle_rxmsg(struct enetc_pf *pf, int vf_id, u16 *status) { - struct enetc_msg_swbd *msg = &pf->rxmsg[vf_id]; + struct enetc_msg_swbd *msg_swbd = &pf->rxmsg[vf_id]; struct device *dev = &pf->si->pdev->dev; struct enetc_msg_cmd_header *cmd_hdr; u16 cmd_type; + u8 *msg; - cmd_hdr = (struct enetc_msg_cmd_header *)msg->vaddr; + msg = kzalloc_objs(*msg, msg_swbd->size); + if (!msg) { + dev_err_ratelimited(dev, + "Failed to allocate message buffer\n"); + *status = ENETC_MSG_CMD_STATUS_FAIL; + return; + } + + /* Currently, only ENETC_MSG_CMD_MNG_MAC command is supported, so + * only sizeof(struct enetc_msg_cmd_set_primary_mac) bytes need to + * be copied. This data already includes the cmd_type field, so it + * can correctly return an error code. + */ + memcpy(msg, msg_swbd->vaddr, + sizeof(struct enetc_msg_cmd_set_primary_mac)); + cmd_hdr = (struct enetc_msg_cmd_header *)msg; cmd_type = cmd_hdr->type; switch (cmd_type) { case ENETC_MSG_CMD_MNG_MAC: - *status = enetc_msg_pf_set_vf_primary_mac_addr(pf, vf_id); + *status = enetc_msg_pf_set_vf_primary_mac_addr(pf, vf_id, msg); break; default: *status = ENETC_MSG_CMD_STATUS_FAIL; @@ -525,6 +544,8 @@ void enetc_msg_handle_rxmsg(struct enetc_pf *pf, int vf_id, u16 *status) "command not supported (cmd_type: 0x%x)\n", cmd_type); } + + kfree(msg); } #ifdef CONFIG_PCI_IOV