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Commit 2cc3aeb5 authored by Ilias Apalodimas's avatar Ilias Apalodimas Committed by David S. Miller
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skbuff: Fix a potential race while recycling page_pool packets



As Alexander points out, when we are trying to recycle a cloned/expanded
SKB we might trigger a race.  The recycling code relies on the
pp_recycle bit to trigger,  which we carry over to cloned SKBs.
If that cloned SKB gets expanded or if we get references to the frags,
call skb_release_data() and overwrite skb->head, we are creating separate
instances accessing the same page frags.  Since the skb_release_data()
will first try to recycle the frags,  there's a potential race between
the original and cloned SKB, since both will have the pp_recycle bit set.

Fix this by explicitly those SKBs not recyclable.
The atomic_sub_return effectively limits us to a single release case,
and when we are calling skb_release_data we are also releasing the
option to perform the recycling, or releasing the pages from the page pool.

Fixes: 6a5bcd84 ("page_pool: Allow drivers to hint on SKB recycling")
Reported-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Suggested-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Reviewed-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Acked-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarIlias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 20192d9c
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