diff options
| author | Sven Eckelmann <sven@narfation.org> | 2026-06-14 11:22:43 +0200 |
|---|---|---|
| committer | Sven Eckelmann <sven@narfation.org> | 2026-06-14 12:33:18 +0200 |
| commit | edb557b2ba38fea2c5eb710cf366c797e187218c (patch) | |
| tree | 77b1146f57c93788c190147d0baeda3f27a449fd /net | |
| parent | 32a6799255525d6ea4da0f7e9e0e521ad9560a46 (diff) | |
| download | ath-edb557b2ba38fea2c5eb710cf366c797e187218c.tar.gz | |
batman-adv: tvlv: avoid race of cifsnotfound handler state
TVLV handlers can have the flag BATADV_TVLV_HANDLER_OGM_CIFNOTFND set to
signal that the OGM handler should be called (with NULL for data) when the
specific TVLV container was not found in the OGM. This is used by:
* DAT
* GW
* Multicast (OGM + Tracker)
The state whether the handler was executed was stored in the struct
batadv_tvlv_handler. But the TVLV processing is started without any lock.
Multiple parallel contexts processing TVLVs would therefore overwrite each
others BATADV_TVLV_HANDLER_OGM_CALLED flag in the shared
batadv_tvlv_handler.
Drop the shared BATADV_TVLV_HANDLER_OGM_CALLED flag and instead determine,
per TVLV buffer, whether a matching container was present by scanning the
packet's buffer.
Cc: stable@kernel.org
Fixes: ef26157747d4 ("batman-adv: tvlv - basic infrastructure")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/batman-adv/tvlv.c | 63 | ||||
| -rw-r--r-- | net/batman-adv/types.h | 7 |
2 files changed, 57 insertions, 13 deletions
diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c index a957555d8958d..1c9fb21985f6a 100644 --- a/net/batman-adv/tvlv.c +++ b/net/batman-adv/tvlv.c @@ -411,7 +411,6 @@ static int batadv_tvlv_call_handler(struct batadv_priv *bat_priv, tvlv_handler->ogm_handler(bat_priv, orig_node, BATADV_NO_FLAGS, tvlv_value, tvlv_value_len); - tvlv_handler->flags |= BATADV_TVLV_HANDLER_OGM_CALLED; break; case BATADV_UNICAST_TVLV: if (!skb) @@ -444,6 +443,48 @@ static int batadv_tvlv_call_handler(struct batadv_priv *bat_priv, } /** + * batadv_tvlv_containers_contain() - check if a tvlv buffer holds a container + * @tvlv_value: tvlv content + * @tvlv_value_len: tvlv content length + * @type: tvlv container type to look for + * @version: tvlv container version to look for + * + * Return: true if a container of the given type and version is present in the + * tvlv buffer, false otherwise. + */ +static bool batadv_tvlv_containers_contain(void *tvlv_value, + u16 tvlv_value_len, u8 type, + u8 version) +{ + struct batadv_tvlv_hdr *tvlv_hdr; + u16 tvlv_value_cont_len; + + while (tvlv_value_len >= sizeof(*tvlv_hdr)) { + tvlv_hdr = tvlv_value; + tvlv_value_cont_len = ntohs(tvlv_hdr->len); + tvlv_value = tvlv_hdr + 1; + tvlv_value_len -= sizeof(*tvlv_hdr); + + if (tvlv_value_cont_len > tvlv_value_len) + break; + + /* the next tvlv header is accessed assuming (at least) 2-byte + * alignment, so it must start at an even offset. + */ + if (tvlv_value_cont_len & 1) + break; + + if (tvlv_hdr->type == type && tvlv_hdr->version == version) + return true; + + tvlv_value = (u8 *)tvlv_value + tvlv_value_cont_len; + tvlv_value_len -= tvlv_value_cont_len; + } + + return false; +} + +/** * batadv_tvlv_containers_process() - parse the given tvlv buffer to call the * appropriate handlers * @bat_priv: the bat priv with all the mesh interface information @@ -462,7 +503,9 @@ int batadv_tvlv_containers_process(struct batadv_priv *bat_priv, struct sk_buff *skb, void *tvlv_value, u16 tvlv_value_len) { + u16 tvlv_value_start_len = tvlv_value_len; struct batadv_tvlv_handler *tvlv_handler; + void *tvlv_value_start = tvlv_value; struct batadv_tvlv_hdr *tvlv_hdr; u16 tvlv_value_cont_len; u8 cifnotfound = BATADV_TVLV_HANDLER_OGM_CIFNOTFND; @@ -506,12 +549,20 @@ int batadv_tvlv_containers_process(struct batadv_priv *bat_priv, if (!tvlv_handler->ogm_handler) continue; - if ((tvlv_handler->flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND) && - !(tvlv_handler->flags & BATADV_TVLV_HANDLER_OGM_CALLED)) - tvlv_handler->ogm_handler(bat_priv, orig_node, - cifnotfound, NULL, 0); + if (!(tvlv_handler->flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)) + continue; - tvlv_handler->flags &= ~BATADV_TVLV_HANDLER_OGM_CALLED; + /* if the corresponding container was present then the handler + * was already called from the loop above + */ + if (batadv_tvlv_containers_contain(tvlv_value_start, + tvlv_value_start_len, + tvlv_handler->type, + tvlv_handler->version)) + continue; + + tvlv_handler->ogm_handler(bat_priv, orig_node, + cifnotfound, NULL, 0); } rcu_read_unlock(); diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 3de3c1ac0244f..b1f9f8964c3fd 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -2294,13 +2294,6 @@ enum batadv_tvlv_handler_flags { * will call this handler even if its type was not found (with no data) */ BATADV_TVLV_HANDLER_OGM_CIFNOTFND = BIT(1), - - /** - * @BATADV_TVLV_HANDLER_OGM_CALLED: interval tvlv handling flag - the - * API marks a handler as being called, so it won't be called if the - * BATADV_TVLV_HANDLER_OGM_CIFNOTFND flag was set - */ - BATADV_TVLV_HANDLER_OGM_CALLED = BIT(2), }; #endif /* _NET_BATMAN_ADV_TYPES_H_ */ |