CVE-2026-64545 is a vulnerability in Linux Kernel
Published on July 27, 2026
net, bpf: check master for NULL in xdp_master_redirect()
In the Linux kernel, the following vulnerability has been resolved:
net, bpf: check master for NULL in xdp_master_redirect()
xdp_master_redirect() dereferences the result of
netdev_master_upper_dev_get_rcu() without a NULL check, but that helper
returns NULL when the receiving device has no upper-master adjacency.
The reach guard only checks netif_is_bond_slave(). On bond slave release
bond_upper_dev_unlink() drops the upper-master adjacency before clearing
IFF_SLAVE, so an XDP_TX reaching xdp_master_redirect() in that window
still passes netif_is_bond_slave() while master is already NULL, and
faults on master->flags at offset 0xb0:
BUG: kernel NULL pointer dereference, address: 00000000000000b0
RIP: 0010:xdp_master_redirect (net/core/filter.c:4432)
Call Trace:
xdp_master_redirect (net/core/filter.c:4432)
bpf_prog_run_generic_xdp (include/net/xdp.h:700)
do_xdp_generic (net/core/dev.c:5608)
__netif_receive_skb_one_core (net/core/dev.c:6204)
process_backlog (net/core/dev.c:6319)
__napi_poll (net/core/dev.c:7729)
net_rx_action (net/core/dev.c:7792)
handle_softirqs (kernel/softirq.c:622)
__dev_queue_xmit (include/linux/bottom_half.h:33)
packet_sendmsg (net/packet/af_packet.c:3082)
__sys_sendto (net/socket.c:2252)
Kernel panic - not syncing: Fatal exception in interrupt
The missing check dates back to the original code; commit 1921f91298d1
("net, bpf: fix null-ptr-deref in xdp_master_redirect() for down master")
later added the master->flags read where the fault now lands but kept the
unconditional deref. Check master for NULL before use; a NULL master is
treated the same as one that is not up.
Products Associated with CVE-2026-64545
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Affected Versions
Linux:- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below c99ca049e910d61ddbd28cc2c47242f2bfbb4970 is affected.
- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below e2a56441233131fe18a76001de347ecda217e40c is affected.
- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below 3876318ea54e83eb70982b8280a3c5e4e32269bf is affected.
- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below 4edbcacca09f92b85d3951b6add11894b20a84bc is affected.
- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below 03b743586a2469744e96e9c1015096d07240935d is affected.
- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below 89c103d702b25ceb2d097faf854deb47b53b17ff is affected.
- Version 879af96ffd72706c6e3278ea6b45b0b0e37ec5d7 and below e82d8cc4321c373dc46e741cd2dfdaa7921fddb7 is affected.
- Version 5.15 is affected.
- Before 5.15 is unaffected.
- Version 5.15.212, <= 5.15.* is unaffected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.97, <= 6.12.* is unaffected.
- Version 6.18.40, <= 6.18.* is unaffected.
- Version 7.1.5, <= 7.1.* is unaffected.
- Version 7.2-rc1, <= * is unaffected.