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netif: fix removing ext-callback while callback is called

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When a registered netif ext-callback unregisters itself when being
called (e.g. because some state is reached by this event), the invoke
iteration might access uninitialized memory or at least stop the
iteration (because next is set to null).

Fix his by caching the next pointer during iteration before calling
callbacks.

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>
This commit is contained in:
Simon Goldschmidt 2021-10-01 19:44:07 +02:00
parent 7ec4e9be30
commit 39a9c5a3c5
1 changed files with 5 additions and 3 deletions
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8
src/core/netif.c
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@ -1825,11 +1825,11 @@ netif_remove_ext_callback(netif_ext_callback_t* callback)
if (iter == callback) {
LWIP_ASSERT("last != NULL", last != NULL);
last->next = callback->next;
callback->next = NULL;
return;
break;
}
}
}
callback->next = NULL;
}
/**
@ -1846,8 +1846,10 @@ netif_invoke_ext_callback(struct netif *netif, netif_nsc_reason_t reason, const
LWIP_ASSERT("netif must be != NULL", netif != NULL);
while (callback != NULL) {
/* cache next pointer: the callback might unregister itself */
netif_ext_callback_t *next = callback->next;
callback->callback_fn(netif, reason, args);
callback = callback->next;
callback = next;
}
}
#endif /* LWIP_NETIF_EXT_STATUS_CALLBACK */