Messages in this thread Patch in this message | | | From | Ryosuke Yasuoka <> | Subject | [PATCH net v4] nfc: nci: Fix uninit-value in nci_rx_work | Date | Thu, 9 May 2024 20:30:33 +0900 |
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syzbot reported the following uninit-value access issue [1]
nci_rx_work() parses received packet from ndev->rx_q. It should be validated header size, payload size and total packet size before processing the packet. If an invalid packet is detected, it should be silently discarded.
Fixes: d24b03535e5e ("nfc: nci: Fix uninit-value in nci_dev_up and nci_ntf_packet") Reported-and-tested-by: syzbot+d7b4dc6cd50410152534@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d7b4dc6cd50410152534 [1] Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com> --- v4 - v3 patch uses goto statement and it makes codes complicated. So this patch simply calls kfree_skb inside loop and remove goto statement. - [2] inserted kcov_remote_stop() to fix kcov check. However, as we discuss about my v3 patch [3], it should not exit the for statement and should continue processing subsequent packets. This patch removes them and simply insert continue statement.
[2] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=19e35f24750d
v3 https://lore.kernel.org/netdev/20240502082323.250739-1-ryasuoka@redhat.com/T/ - As Simon pointed out, the valid packets will reach invalid_pkt_free and kfree_skb(skb) after being handled correctly in switch statement. It can lead to double free issues, which is not intended. So this patch uses "continue" instead of "break" in switch statement.
- In the current implementation, once zero payload size is detected, the for statement exits. It should continue processing subsequent packets. So this patch just frees skb in invalid_pkt_free when the invalid packets are detected. [3]
v2 https://lore.kernel.org/lkml/20240428134525.GW516117@kernel.org/T/
- The v1 patch only checked whether skb->len is zero. This patch also checks header size, payload size and total packet size.
v1 https://lore.kernel.org/linux-kernel/CANn89iJrQevxPFLCj2P=U+XSisYD0jqrUQpa=zWMXTjj5+RriA@mail.gmail.com/T/
net/nfc/nci/core.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-)
diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c index b133dc55304c..0aaff30cb68f 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -1463,6 +1463,16 @@ int nci_core_ntf_packet(struct nci_dev *ndev, __u16 opcode, ndev->ops->n_core_ops); } +static bool nci_valid_size(struct sk_buff *skb, unsigned int header_size) +{ + if (skb->len < header_size || + !nci_plen(skb->data) || + skb->len < header_size + nci_plen(skb->data)) { + return false; + } + return true; +} + /* ---- NCI TX Data worker thread ---- */ static void nci_tx_work(struct work_struct *work) @@ -1516,24 +1526,32 @@ static void nci_rx_work(struct work_struct *work) nfc_send_to_raw_sock(ndev->nfc_dev, skb, RAW_PAYLOAD_NCI, NFC_DIRECTION_RX); - if (!nci_plen(skb->data)) { + if (!skb->len) { kfree_skb(skb); - kcov_remote_stop(); - break; + continue; } /* Process frame */ switch (nci_mt(skb->data)) { case NCI_MT_RSP_PKT: - nci_rsp_packet(ndev, skb); + if (nci_valid_size(skb, NCI_CTRL_HDR_SIZE)) + nci_rsp_packet(ndev, skb); + else + kfree_skb(skb); break; case NCI_MT_NTF_PKT: - nci_ntf_packet(ndev, skb); + if (nci_valid_size(skb, NCI_CTRL_HDR_SIZE)) + nci_ntf_packet(ndev, skb); + else + kfree_skb(skb); break; case NCI_MT_DATA_PKT: - nci_rx_data_packet(ndev, skb); + if (nci_valid_size(skb, NCI_DATA_HDR_SIZE)) + nci_rx_data_packet(ndev, skb); + else + kfree_skb(skb); break; default: -- 2.44.0
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