diff options
| author | Martin KaFai Lau <martin.lau@kernel.org> | 2023-07-28 23:47:17 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-07-31 14:44:02 -0700 |
| commit | 079082c60affefeb9d2bd4176a4f2b390a9ccfda (patch) | |
| tree | 07d7e323408c1f91ac844d85f3b42b39e5ac59a0 /kernel/bpf/tcx.c | |
| parent | df41fa677d9b4717c930afbe88b06f5cefdacb21 (diff) | |
tcx: Fix splat during dev unregister
During unregister_netdevice_many_notify(), the ordering of our concerned
function calls is like this:
unregister_netdevice_many_notify
dev_shutdown
qdisc_put
clsact_destroy
tcx_uninstall
The syzbot reproducer triggered a case that the qdisc refcnt is not
zero during dev_shutdown().
tcx_uninstall() will then WARN_ON_ONCE(tcx_entry(entry)->miniq_active)
because the miniq is still active and the entry should not be freed.
The latter assumed that qdisc destruction happens before tcx teardown.
This fix is to avoid tcx_uninstall() doing tcx_entry_free() when the
miniq is still alive and let the clsact_destroy() do the free later, so
that we do not assume any specific ordering for either of them.
If still active, tcx_uninstall() does clear the entry when flushing out
the prog/link. clsact_destroy() will then notice the "!tcx_entry_is_active()"
and then does the tcx_entry_free() eventually.
Fixes: e420bed02507 ("bpf: Add fd-based tcx multi-prog infra with link support")
Reported-by: syzbot+376a289e86a0fd02b9ba@syzkaller.appspotmail.com
Reported-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+376a289e86a0fd02b9ba@syzkaller.appspotmail.com
Tested-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/222255fe07cb58f15ee662e7ee78328af5b438e4.1690549248.git.daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'kernel/bpf/tcx.c')
| -rw-r--r-- | kernel/bpf/tcx.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/bpf/tcx.c b/kernel/bpf/tcx.c index 69a272712b29..13f0b5dc8262 100644 --- a/kernel/bpf/tcx.c +++ b/kernel/bpf/tcx.c @@ -94,15 +94,19 @@ out: void tcx_uninstall(struct net_device *dev, bool ingress) { + struct bpf_mprog_entry *entry, *entry_new = NULL; struct bpf_tuple tuple = {}; - struct bpf_mprog_entry *entry; struct bpf_mprog_fp *fp; struct bpf_mprog_cp *cp; + bool active; entry = tcx_entry_fetch(dev, ingress); if (!entry) return; - tcx_entry_update(dev, NULL, ingress); + active = tcx_entry(entry)->miniq_active; + if (active) + bpf_mprog_clear_all(entry, &entry_new); + tcx_entry_update(dev, entry_new, ingress); tcx_entry_sync(); bpf_mprog_foreach_tuple(entry, fp, cp, tuple) { if (tuple.link) @@ -111,8 +115,8 @@ void tcx_uninstall(struct net_device *dev, bool ingress) bpf_prog_put(tuple.prog); tcx_skeys_dec(ingress); } - WARN_ON_ONCE(tcx_entry(entry)->miniq_active); - tcx_entry_free(entry); + if (!active) + tcx_entry_free(entry); } int tcx_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) |