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| author | Eric Dumazet <edumazet@google.com> | 2014-05-29 08:45:14 -0700 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-06-23 10:27:59 +0200 |
| commit | 12b4aba2d6f870dd8f505ae5dd5fc887d6484a93 (patch) | |
| tree | ec3b5c375377d4049883825cfcb123ca1214d3c4 /net | |
| parent | fe2fe574d1e2c377bbfe641a34935db9d76be539 (diff) | |
| download | lwn-12b4aba2d6f870dd8f505ae5dd5fc887d6484a93.tar.gz lwn-12b4aba2d6f870dd8f505ae5dd5fc887d6484a93.zip | |
net: fix inet_getid() and ipv6_select_ident() bugs
[ Upstream commit 39c36094d78c39e038c1e499b2364e13bce36f54 ]
I noticed we were sending wrong IPv4 ID in TCP flows when MTU discovery
is disabled.
Note how GSO/TSO packets do not have monotonically incrementing ID.
06:37:41.575531 IP (id 14227, proto: TCP (6), length: 4396)
06:37:41.575534 IP (id 14272, proto: TCP (6), length: 65212)
06:37:41.575544 IP (id 14312, proto: TCP (6), length: 57972)
06:37:41.575678 IP (id 14317, proto: TCP (6), length: 7292)
06:37:41.575683 IP (id 14361, proto: TCP (6), length: 63764)
It appears I introduced this bug in linux-3.1.
inet_getid() must return the old value of peer->ip_id_count,
not the new one.
Lets revert this part, and remove the prevention of
a null identification field in IPv6 Fragment Extension Header,
which is dubious and not even done properly.
Fixes: 87c48fa3b463 ("ipv6: make fragment identifications less predictable")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/output_core.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c index 827f795209cf..b31a01263185 100644 --- a/net/ipv6/output_core.c +++ b/net/ipv6/output_core.c @@ -10,7 +10,7 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) { static atomic_t ipv6_fragmentation_id; - int old, new; + int ident; #if IS_ENABLED(CONFIG_IPV6) if (rt && !(rt->dst.flags & DST_NOPEER)) { @@ -26,13 +26,8 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) } } #endif - do { - old = atomic_read(&ipv6_fragmentation_id); - new = old + 1; - if (!new) - new = 1; - } while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old); - fhdr->identification = htonl(new); + ident = atomic_inc_return(&ipv6_fragmentation_id); + fhdr->identification = htonl(ident); } EXPORT_SYMBOL(ipv6_select_ident); |