CVE-2026-64190

In the Linux kernel, the following vulnerability has been resolved:

net: team: fix NULL pointer dereference in team_xmit during mode change

__team_change_mode() clears team->ops with memset() before restoring

safe dummy handlers via team_adjust_ops(). A concurrent team_xmit()

running under RCU on another CPU can read team->ops.transmit during

this window and call a NULL function pointer, crashing the kernel.

The race requires a mode change (CAP_NET_ADMIN) concurrent with

transmit on the team device.

BUG: kernel NULL pointer dereference, address: 0000000000000000

Oops: 0010 [#1] SMP KASAN NOPTI

RIP: 0010:0x0

Call Trace:

team_xmit (drivers/net/team/team_core.c:1853)

dev_hard_start_xmit (net/core/dev.c:3904)

__dev_queue_xmit (net/core/dev.c:4871)

packet_sendmsg (net/packet/af_packet.c:3109)

__sys_sendto (net/socket.c:2265)

The original code assumed that no ports means no traffic, so mode

changes could freely memset()/memcpy() the ops. AF_PACKET with

forced carrier breaks that assumption.

Prevent the race instead of making it safe: replace memset()/memcpy()

with per-field updates that never touch transmit or receive. Those

two handlers are managed solely by team_adjust_ops(), which already

installs dummies when tx_en_port_count == 0 (always true during mode

change since no ports are present). WRITE_ONCE/READ_ONCE prevent

store/load tearing on the handler pointers.

synchronize_net() before exit_op() drains in-flight readers that may

still reference old mode state from before port removal switched the

handlers to dummies.