Merge tag 'net-6.10-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Paolo Abeni:
 "Including fixes from bpf and netfilter.

  Current release - regressions:

   - core: fix rc7's __skb_datagram_iter() regression

  Current release - new code bugs:

   - eth: bnxt: fix crashes when reducing ring count with active RSS
     contexts

  Previous releases - regressions:

   - sched: fix UAF when resolving a clash

   - skmsg: skip zero length skb in sk_msg_recvmsg2

   - sunrpc: fix kernel free on connection failure in
     xs_tcp_setup_socket

   - tcp: avoid too many retransmit packets

   - tcp: fix incorrect undo caused by DSACK of TLP retransmit

   - udp: Set SOCK_RCU_FREE earlier in udp_lib_get_port().

   - eth: ks8851: fix deadlock with the SPI chip variant

   - eth: i40e: fix XDP program unloading while removing the driver

  Previous releases - always broken:

   - bpf:
       - fix too early release of tcx_entry
       - fail bpf_timer_cancel when callback is being cancelled
       - bpf: fix order of args in call to bpf_map_kvcalloc

   - netfilter: nf_tables: prefer nft_chain_validate

   - ppp: reject claimed-as-LCP but actually malformed packets

   - wireguard: avoid unaligned 64-bit memory accesses"

* tag 'net-6.10-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (33 commits)
  net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup_socket
  net/sched: Fix UAF when resolving a clash
  net: ks8851: Fix potential TX stall after interface reopen
  udp: Set SOCK_RCU_FREE earlier in udp_lib_get_port().
  netfilter: nf_tables: prefer nft_chain_validate
  netfilter: nfnetlink_queue: drop bogus WARN_ON
  ethtool: netlink: do not return SQI value if link is down
  ppp: reject claimed-as-LCP but actually malformed packets
  selftests/bpf: Add timer lockup selftest
  net: ethernet: mtk-star-emac: set mac_managed_pm when probing
  e1000e: fix force smbus during suspend flow
  tcp: avoid too many retransmit packets
  bpf: Defer work in bpf_timer_cancel_and_free
  bpf: Fail bpf_timer_cancel when callback is being cancelled
  bpf: fix order of args in call to bpf_map_kvcalloc
  net: ethernet: lantiq_etop: fix double free in detach
  i40e: Fix XDP program unloading while removing the driver
  net: fix rc7's __skb_datagram_iter()
  net: ks8851: Fix deadlock with the SPI chip variant
  octeontx2-af: Fix incorrect value output on error path in rvu_check_rsrc_availability()
  ...

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 0a65b6d690fe..eb9acfcaeb09 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -70,6 +70,7 @@
 #define MPHDRLEN_SSN	4	/* ditto with short sequence numbers */
 
 #define PPP_PROTO_LEN	2
+#define PPP_LCP_HDRLEN	4
 
 /*
  * An instance of /dev/ppp can be associated with either a ppp
@@ -493,6 +494,15 @@ static ssize_t ppp_read(struct file *file, char __user *buf,
 	return ret;
 }
 
+static bool ppp_check_packet(struct sk_buff *skb, size_t count)
+{
+	/* LCP packets must include LCP header which 4 bytes long:
+	 * 1-byte code, 1-byte identifier, and 2-byte length.
+	 */
+	return get_unaligned_be16(skb->data) != PPP_LCP ||
+		count >= PPP_PROTO_LEN + PPP_LCP_HDRLEN;
+}
+
 static ssize_t ppp_write(struct file *file, const char __user *buf,
 			 size_t count, loff_t *ppos)
 {
@@ -515,6 +525,11 @@ static ssize_t ppp_write(struct file *file, const char __user *buf,
 		kfree_skb(skb);
 		goto out;
 	}
+	ret = -EINVAL;
+	if (unlikely(!ppp_check_packet(skb, count))) {
+		kfree_skb(skb);
+		goto out;
+	}
 
 	switch (pf->kind) {
 	case INTERFACE: