Eric Lee / smarc-ti-linux-kernel

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Commit 4e27762417669cb459971635be550eb7b5598286

Authored by Herbert Xu
Committed by Greg Kroah-Hartman
1 parent d600176461
Exists in ti-lsk-linux-4.1.y and in 5 other branches processor-sdk-linux-02.00.01, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-linux-02.00.01, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-02.00.01

netlink: Fix autobind race condition that leads to zero port ID 

[ Upstream commit 1f770c0a09da855a2b51af6d19de97fb955eca85 ]

The commit c0bb07df7d981e4091432754e30c9c720e2c0c78 ("netlink:
Reset portid after netlink_insert failure") introduced a race
condition where if two threads try to autobind the same socket
one of them may end up with a zero port ID.  This led to kernel
deadlocks that were observed by multiple people.

This patch reverts that commit and instead fixes it by introducing
a separte rhash_portid variable so that the real portid is only set
after the socket has been successfully hashed.

Fixes: c0bb07df7d98 ("netlink: Reset portid after netlink_insert failure")
Reported-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 2 changed files with 7 additions and 5 deletions Side-by-side Diff

net/netlink/af_netlink.c
Diff comments   View file @ 4e27762
... ... @@ -1017,7 +1017,7 @@
1017 1017 const struct netlink_compare_arg *x = arg->key;
1018 1018 const struct netlink_sock *nlk = ptr;
1019 1019  
1020   - return nlk->portid != x->portid ||
  1020 + return nlk->rhash_portid != x->portid ||
1021 1021 !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
1022 1022 }
1023 1023  
... ... @@ -1043,7 +1043,7 @@
1043 1043 {
1044 1044 struct netlink_compare_arg arg;
1045 1045  
1046   - netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
  1046 + netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->rhash_portid);
1047 1047 return rhashtable_lookup_insert_key(&table->hash, &arg,
1048 1048 &nlk_sk(sk)->node,
1049 1049 netlink_rhashtable_params);
... ... @@ -1105,7 +1105,7 @@
1105 1105 unlikely(atomic_read(&table->hash.nelems) >= UINT_MAX))
1106 1106 goto err;
1107 1107  
1108   - nlk_sk(sk)->portid = portid;
  1108 + nlk_sk(sk)->rhash_portid = portid;
1109 1109 sock_hold(sk);
1110 1110  
1111 1111 err = __netlink_insert(table, sk);
1112 1112  
... ... @@ -1117,10 +1117,11 @@
1117 1117 err = -EOVERFLOW;
1118 1118 if (err == -EEXIST)
1119 1119 err = -EADDRINUSE;
1120   - nlk_sk(sk)->portid = 0;
1121 1120 sock_put(sk);
1122 1121 }
1123 1122  
  1123 + nlk_sk(sk)->portid = portid;
  1124 +
1124 1125 err:
1125 1126 release_sock(sk);
1126 1127 return err;
... ... @@ -3167,7 +3168,7 @@
3167 3168 const struct netlink_sock *nlk = data;
3168 3169 struct netlink_compare_arg arg;
3169 3170  
3170   - netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
  3171 + netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->rhash_portid);
3171 3172 return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
3172 3173 }
3173 3174  
net/netlink/af_netlink.h
Diff comments   View file @ 4e27762
... ... @@ -25,6 +25,7 @@
25 25 struct netlink_sock {
26 26 /* struct sock has to be the first member of netlink_sock */
27 27 struct sock sk;
  28 + u32 rhash_portid;
28 29 u32 portid;
29 30 u32 dst_portid;
30 31 u32 dst_group;