diff options
| author | Martin KaFai Lau <martin.lau@kernel.org> | 2023-07-29 00:47:17 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-08-01 00:44:02 +0300 |
| commit | 079082c60affefeb9d2bd4176a4f2b390a9ccfda (patch) | |
| tree | 07d7e323408c1f91ac844d85f3b42b39e5ac59a0 | |
| parent | df41fa677d9b4717c930afbe88b06f5cefdacb21 (diff) | |
| download | linux-079082c60affefeb9d2bd4176a4f2b390a9ccfda.tar.xz | |
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>
| -rw-r--r-- | include/linux/bpf_mprog.h | 16 | ||||
| -rw-r--r-- | kernel/bpf/tcx.c | 12 |
2 files changed, 24 insertions, 4 deletions
diff --git a/include/linux/bpf_mprog.h b/include/linux/bpf_mprog.h index 2b429488f840..929225f7b095 100644 --- a/include/linux/bpf_mprog.h +++ b/include/linux/bpf_mprog.h @@ -256,6 +256,22 @@ static inline void bpf_mprog_entry_copy(struct bpf_mprog_entry *dst, memcpy(dst->fp_items, src->fp_items, sizeof(src->fp_items)); } +static inline void bpf_mprog_entry_clear(struct bpf_mprog_entry *dst) +{ + memset(dst->fp_items, 0, sizeof(dst->fp_items)); +} + +static inline void bpf_mprog_clear_all(struct bpf_mprog_entry *entry, + struct bpf_mprog_entry **entry_new) +{ + struct bpf_mprog_entry *peer; + + peer = bpf_mprog_peer(entry); + bpf_mprog_entry_clear(peer); + peer->parent->count = 0; + *entry_new = peer; +} + static inline void bpf_mprog_entry_grow(struct bpf_mprog_entry *entry, int idx) { int total = bpf_mprog_total(entry); 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) |