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author | Eric Dumazet <edumazet@google.com> | 2015-12-30 08:51:12 -0500 |
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committer | David S. Miller <davem@davemloft.net> | 2016-01-04 17:23:36 -0500 |
commit | 197c949e7798fbf28cfadc69d9ca0c2abbf93191 (patch) | |
tree | b11734b5208854fbbbdcbcdb02a994e03c87d0c9 /Documentation | |
parent | 815bc580fe4ebffc35cc837a775f5400f5a607c4 (diff) | |
download | linux-197c949e7798fbf28cfadc69d9ca0c2abbf93191.tar.bz2 |
udp: properly support MSG_PEEK with truncated buffers
Backport of this upstream commit into stable kernels :
89c22d8c3b27 ("net: Fix skb csum races when peeking")
exposed a bug in udp stack vs MSG_PEEK support, when user provides
a buffer smaller than skb payload.
In this case,
skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr),
msg->msg_iov);
returns -EFAULT.
This bug does not happen in upstream kernels since Al Viro did a great
job to replace this into :
skb_copy_and_csum_datagram_msg(skb, sizeof(struct udphdr), msg);
This variant is safe vs short buffers.
For the time being, instead reverting Herbert Xu patch and add back
skb->ip_summed invalid changes, simply store the result of
udp_lib_checksum_complete() so that we avoid computing the checksum a
second time, and avoid the problematic
skb_copy_and_csum_datagram_iovec() call.
This patch can be applied on recent kernels as it avoids a double
checksumming, then backported to stable kernels as a bug fix.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation')
0 files changed, 0 insertions, 0 deletions