diff options
| author | Kyle Zeng <kylebot@openai.com> | 2026-08-10 14:41:14 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-09-02 14:32:38 +0200 |
| commit | 8ba68fd6cdd1e3c92b92f25c7e48bf7bd51a183c (patch) | |
| tree | 41d1de5fe74ca4b7315f5ecebda39ad8f48e6137 | |
| parent | 1b466746fe109127fd983100a228cdd1f1f6ece2 (diff) | |
| download | linux-8ba68fd6cdd1e3c92b92f25c7e48bf7bd51a183c.tar.gz linux-8ba68fd6cdd1e3c92b92f25c7e48bf7bd51a183c.zip | |
vxlan: keep the last remote linked during FDB flush
commit d5d4a7b538b52db63927773a8905fcd9f78a42e2 upstream.
A non-nexthop FDB entry is expected to have at least one remote while it
remains reachable through the FDB hash table. A filtered bulk flush
violates this invariant when every remote matches: It unlinks the last
remote in vxlan_fdb_dst_destroy() and only afterwards tells vxlan_flush()
to destroy the parent FDB entry.
An RCU reader can find the parent during this interval.
first_remote_rcu() then applies list_entry_rcu() to the empty list head,
producing an invalid remote pointer that the receive learning path can
read from and write to.
When a matching remote is the sole remaining remote, leave it linked and
ask the caller to destroy the entire FDB entry. vxlan_fdb_destroy() keeps
the remote attached while sending the deletion notification and removing
the parent from the lookup structures.
Fixes: c499fccb71cb ("vxlan: vxlan_core: Support FDB flushing by destination VNI")
Cc: stable@vger.kernel.org
Signed-off-by: Kyle Zeng <kylebot@openai.com>
Co-developed-by: David Lee <david.lee@trailofbits.com>
Signed-off-by: David Lee <david.lee@trailofbits.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260810144115.821654-1-david.lee@trailofbits.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/vxlan/vxlan_core.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index 608087f78d02..f94e071ebde0 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -3059,18 +3059,19 @@ vxlan_fdb_flush_match_remotes(struct vxlan_fdb *f, struct vxlan_dev *vxlan, const struct vxlan_fdb_flush_desc *desc, bool *p_destroy_fdb) { - bool remotes_flushed = false; struct vxlan_rdst *rd, *tmp; list_for_each_entry_safe(rd, tmp, &f->remotes, list) { if (!vxlan_fdb_flush_remote_matches(desc, rd)) continue; + if (list_is_singular(&f->remotes)) { + *p_destroy_fdb = true; + return; + } + vxlan_fdb_dst_destroy(vxlan, f, rd, true); - remotes_flushed = true; } - - *p_destroy_fdb = remotes_flushed && list_empty(&f->remotes); } /* Purge the forwarding table */ |