kernel/linux.git/net/batman-adv/bridge_loop_avoidance.c, branch v7.0.11

batman-adv: bla: avoid NULL-ptr deref for claim via dropped interface

2026-06-01T15:54:31+00:00

commit f80d3d98d2ff78d9e2fe5d68b1f45948c4f7bd24 upstream. Without rtnl_lock held, a hardif might be retrieved as primary interface of a meshif, but then (while operating on this interface) getting decoupled from the mesh interface. In this case, the meshif still exists but the pointer from the primary hardif to the meshif is set to NULL. The mesh_iface must be checked first to be non-NULL before continuing to send an ARP request using meshif. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Reported-by: Ido Schimmel Reported-by: syzbot+9fdcc9f05a98a540b816@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9fdcc9f05a98a540b816 Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman

batman-adv: bla: avoid double decrement of bla.num_requests

2026-06-01T15:54:31+00:00

commit 83ab69bd12b80f6ea169c8bea6977701b53a043d upstream. The bla.num_requests is increased when no request_sent was in progress. And it is decremented in various places (announcement was received, backbone is purged, periodic work). But the check if the request_sent is actually set to a specific state and the atomic_dec/_inc are not safe because they are not atomic (TOCTOU) and multiple such code portions can run concurrently. At the same time, it is necessary to modify request_sent (state) and bla.num_requests atomically. Otherwise batadv_bla_send_request() might set request_sent to 1 and is interrupted. batadv_handle_announce() can then set request_sent back to 0 and decrement num_requests before batadv_bla_send_request() incremented it. The two operations must therefore be locked. And since state (request_sent) and wait_periods are only accessed inside this lock, they can be converted to simpler datatypes. And to avoid that the bla.num_requests is touched by a parallel running context with a valid backbone_gw reference after batadv_bla_purge_backbone_gw() ran, a third state "stopped" is required to correctly signal that a backbone_gw is in the state of being cleaned up. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman

batman-adv: bla: fix report_work leak on backbone_gw purge

2026-06-01T15:54:31+00:00

commit 0459430add32ea41f3e2ef9351610e6d33627a6b upstream. batadv_bla_purge_backbone_gw() removes stale backbone gateway entries, but fails to properly handle their associated report_work: - If report_work is running, the purge must wait for it to finish before freeing the backbone_gw, otherwise the worker may access freed memory (e.g. bat_priv). - If report_work is pending, the purge must cancel it and release the reference held for that pending work item. The previous implementation called hlist_for_each_entry_safe() inside a spin_lock_bh() section, but cancel_work_sync() may sleep and therefore cannot be called from within a spinlock-protected region. Restructure the loop to handle one entry per spinlock critical section: acquire the lock, find the next entry to purge, remove it from the hash list, then release the lock before calling cancel_work_sync() and dropping the hash_entry reference. Repeat until no more entries require purging. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Reviewed-by: Simon Wunderlich Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman

batman-adv: bla: put backbone reference on failed claim hash insert

2026-05-17T15:16:33+00:00

commit ba9d20ee9076dac32c371116bacbe72480eb356c upstream. When batadv_bla_add_claim() fails to insert a new claim into the hash, it leaked a reference to the backbone_gw for which the claim was intended. Call batadv_backbone_gw_put() on the error path to release the reference and avoid leaking the backbone_gw object. Cc: stable@kernel.org Fixes: 3db0decf1185 ("batman-adv: Fix non-atomic bla_claim::backbone_gw access") Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman

batman-adv: bla: only purge non-released claims

2026-05-17T15:16:33+00:00

commit cf6b604011591865ae39ac82de8978c1120d17af upstream. When batadv_bla_purge_claims() goes through the list of claims, it is only traversing the hash list with an rcu_read_lock(). Due to a potential parallel batadv_claim_put(), it can happen that it encounters a claim which was actually in the process of being released+freed by batadv_claim_release(). In this case, backbone_gw is set to NULL before the delayed RCU kfree is started. Calling batadv_bla_claim_get_backbone_gw() is then no longer allowed because it would cause a NULL-ptr derefence. To avoid this, only claims with a valid reference counter must be purged. All others are already taken care of. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman

batman-adv: bla: prevent use-after-free when deleting claims

2026-05-17T15:16:33+00:00

commit 4ae1709a314060a196981b344610d023ea841e57 upstream. When batadv_bla_del_backbone_claims() removes all claims for a backbone, it does this by dropping the link entry in the hash list. This list entry itself was one of the references which need to be dropped at the same time via batadv_claim_put(). But the batadv_claim_put() must not be done before the last access to the claim object in this function. Otherwise the claim might be freed already by the batadv_claim_release() function before the list entry was dropped. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman

Merge tag 'batadv-net-pullrequest-20260408' of https://git.open-mesh.org/linux-merge

2026-04-09T01:50:27+00:00

Simon Wunderlich says: ==================== Here are two batman-adv bugfixes: - reject oversized global TT response buffers, by Ruide Cao - hold claim backbone gateways by reference, by Haoze Xie * tag 'batadv-net-pullrequest-20260408' of https://git.open-mesh.org/linux-merge: batman-adv: hold claim backbone gateways by reference batman-adv: reject oversized global TT response buffers ==================== Link: https://patch.msgid.link/20260408110255.976389-1-sw@simonwunderlich.de Signed-off-by: Jakub Kicinski

batman-adv: hold claim backbone gateways by reference

2026-04-06T13:42:29+00:00

batadv_bla_add_claim() can replace claim->backbone_gw and drop the old gateway's last reference while readers still follow the pointer. The netlink claim dump path dereferences claim->backbone_gw->orig and takes claim->backbone_gw->crc_lock without pinning the underlying backbone gateway. batadv_bla_check_claim() still has the same naked pointer access pattern. Reuse batadv_bla_claim_get_backbone_gw() in both readers so they operate on a stable gateway reference until the read-side work is complete. This keeps the dump and claim-check paths aligned with the lifetime rules introduced for the other BLA claim readers. Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Fixes: 04f3f5bf1883 ("batman-adv: add B.A.T.M.A.N. Dump BLA claims via netlink") Cc: stable@vger.kernel.org Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Signed-off-by: Haoze Xie Signed-off-by: Ao Zhou Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

batman-adv: use skb_crc32c() instead of skb_seq_read()

2025-10-17T14:30:43+00:00

Make batadv_bla_check_duplist() just use the new function skb_crc32c(), instead of calling skb_seq_read() with crc32c(). This is faster and simpler. Suggested-by: Eric Biggers Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich