diff options
| author | Weiming Shi <bestswngs@gmail.com> | 2026-09-20 21:23:04 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-09-23 02:19:02 +0000 |
| commit | 6db1ce73e9853f533eb7f413f14ba00f8ec6f80d (patch) | |
| tree | 5e9408b7b4bd3f14563319e8de114767d0cd0a22 /kernel | |
| parent | 814a81c842bd88f6bd8a4ce550d560df071a5d03 (diff) | |
bpf: Reject dev-bound-only programs on other devices
__bpf_offload_dev_match() falls back to comparing offdev pointers after an
exact netdev mismatch. Bound-only programs normally have NULL offdevs, so
unrelated netdevs compare equal. A bound-only program on an
offload-registered netdev can instead inherit a real offdev and match a
sibling port. With CAP_BPF and CAP_NET_ADMIN, a caller can use
bpf(BPF_LINK_CREATE) with a different target ifindex to run metadata kfuncs
specialized for the bound driver on the target driver's xdp_buff. Running a
veth-bound program on tun reads beyond tun's bare stack xdp_buff as a
veth_xdp_buff.
Oops: general protection fault, probably for non-canonical address
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
RIP: 0010:veth_xdp_rx_timestamp (drivers/net/veth.c:1673)
Call Trace:
...
tun_build_skb (drivers/net/tun.c:1739)
tun_get_user (drivers/net/tun.c:1856)
tun_chr_write_iter (drivers/net/tun.c:2091)
vfs_write (fs/read_write.c:595 fs/read_write.c:687)
ksys_write (fs/read_write.c:739)
do_syscall_64 (arch/x86/entry/syscall_64.c:84)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
Kernel panic - not syncing: Fatal exception in interrupt
Restrict non-offloaded programs to exact netdev matches and retain the
shared-offdev fallback only for genuinely offloaded multi-port programs.
Fixes: 2b3486bc2d23 ("bpf: Introduce device-bound XDP programs")
Reported-by: <co+ac0a8c41de69121d@bugs.sh>
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260917161335.1020405-2-bestswngs@gmail.com/
Link: https://patch.msgid.link/20260920132303.4109240-3-bestswngs@gmail.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/offload.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 0d6f5569588c..d855399812ee 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -698,6 +698,8 @@ static bool __bpf_offload_dev_match(struct bpf_prog *prog, return false; if (offload->netdev == netdev) return true; + if (!bpf_prog_is_offloaded(prog->aux)) + return false; ondev1 = bpf_offload_find_netdev(offload->netdev); ondev2 = bpf_offload_find_netdev(netdev); |