diff options
| author | Eric Dumazet <edumazet@google.com> | 2022-02-03 14:55:47 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-02-04 20:07:12 -0800 |
| commit | f8d9d938514f46c4892aff6bfe32f425e84d81cc (patch) | |
| tree | 10f3b692d8eb98dcfe9b75139e007affeb46efce /net | |
| parent | 40106e005bd9764f84ef9e6c0979fe1126d7ff02 (diff) | |
tcp: take care of mixed splice()/sendmsg(MSG_ZEROCOPY) case
syzbot found that mixing sendpage() and sendmsg(MSG_ZEROCOPY)
calls over the same TCP socket would again trigger the
infamous warning in inet_sock_destruct()
WARN_ON(sk_forward_alloc_get(sk));
While Talal took into account a mix of regular copied data
and MSG_ZEROCOPY one in the same skb, the sendpage() path
has been forgotten.
We want the charging to happen for sendpage(), because
pages could be coming from a pipe. What is missing is the
downgrading of pure zerocopy status to make sure
sk_forward_alloc will stay synced.
Add tcp_downgrade_zcopy_pure() helper so that we can
use it from the two callers.
Fixes: 9b65b17db723 ("net: avoid double accounting for pure zerocopy skbs")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Talal Ahmad <talalahmad@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Link: https://lore.kernel.org/r/20220203225547.665114-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index bdf108f544a4..02cb275e5487 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -937,6 +937,22 @@ void tcp_remove_empty_skb(struct sock *sk) } } +/* skb changing from pure zc to mixed, must charge zc */ +static int tcp_downgrade_zcopy_pure(struct sock *sk, struct sk_buff *skb) +{ + if (unlikely(skb_zcopy_pure(skb))) { + u32 extra = skb->truesize - + SKB_TRUESIZE(skb_end_offset(skb)); + + if (!sk_wmem_schedule(sk, extra)) + return -ENOMEM; + + sk_mem_charge(sk, extra); + skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY; + } + return 0; +} + static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags, struct page *page, int offset, size_t *size) { @@ -972,7 +988,7 @@ new_segment: tcp_mark_push(tp, skb); goto new_segment; } - if (!sk_wmem_schedule(sk, copy)) + if (tcp_downgrade_zcopy_pure(sk, skb) || !sk_wmem_schedule(sk, copy)) return NULL; if (can_coalesce) { @@ -1320,19 +1336,8 @@ new_segment: copy = min_t(int, copy, pfrag->size - pfrag->offset); - /* skb changing from pure zc to mixed, must charge zc */ - if (unlikely(skb_zcopy_pure(skb))) { - u32 extra = skb->truesize - - SKB_TRUESIZE(skb_end_offset(skb)); - - if (!sk_wmem_schedule(sk, extra)) - goto wait_for_space; - - sk_mem_charge(sk, extra); - skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY; - } - - if (!sk_wmem_schedule(sk, copy)) + if (tcp_downgrade_zcopy_pure(sk, skb) || + !sk_wmem_schedule(sk, copy)) goto wait_for_space; err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb, |