diff options
| author | Xin Long <lucien.xin@gmail.com> | 2020-09-13 19:37:31 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-01 11:11:49 +0200 |
| commit | 6afd3e4010e57d278c3e79b4fbe323ade9c14f93 (patch) | |
| tree | bbd3ade1d784ec6d9c9434d15dc350f0d38fc3f3 | |
| parent | a49ef91286776c3f095460112846cd85a063c29a (diff) | |
tipc: use skb_unshare() instead in tipc_buf_append()
[ Upstream commit ff48b6222e65ebdba5a403ef1deba6214e749193 ]
In tipc_buf_append() it may change skb's frag_list, and it causes
problems when this skb is cloned. skb_unclone() doesn't really
make this skb's flag_list available to change.
Shuang Li has reported an use-after-free issue because of this
when creating quite a few macvlan dev over the same dev, where
the broadcast packets will be cloned and go up to the stack:
[ ] BUG: KASAN: use-after-free in pskb_expand_head+0x86d/0xea0
[ ] Call Trace:
[ ] dump_stack+0x7c/0xb0
[ ] print_address_description.constprop.7+0x1a/0x220
[ ] kasan_report.cold.10+0x37/0x7c
[ ] check_memory_region+0x183/0x1e0
[ ] pskb_expand_head+0x86d/0xea0
[ ] process_backlog+0x1df/0x660
[ ] net_rx_action+0x3b4/0xc90
[ ]
[ ] Allocated by task 1786:
[ ] kmem_cache_alloc+0xbf/0x220
[ ] skb_clone+0x10a/0x300
[ ] macvlan_broadcast+0x2f6/0x590 [macvlan]
[ ] macvlan_process_broadcast+0x37c/0x516 [macvlan]
[ ] process_one_work+0x66a/0x1060
[ ] worker_thread+0x87/0xb10
[ ]
[ ] Freed by task 3253:
[ ] kmem_cache_free+0x82/0x2a0
[ ] skb_release_data+0x2c3/0x6e0
[ ] kfree_skb+0x78/0x1d0
[ ] tipc_recvmsg+0x3be/0xa40 [tipc]
So fix it by using skb_unshare() instead, which would create a new
skb for the cloned frag and it'll be safe to change its frag_list.
The similar things were also done in sctp_make_reassembled_event(),
which is using skb_copy().
Reported-by: Shuang Li <shuali@redhat.com>
Fixes: 37e22164a8a3 ("tipc: rename and move message reassembly function")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/tipc/msg.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/tipc/msg.c b/net/tipc/msg.c index 67bddcb2ff46..fc1aa8bcb185 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -138,7 +138,8 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf) if (fragid == FIRST_FRAGMENT) { if (unlikely(head)) goto err; - if (unlikely(skb_unclone(frag, GFP_ATOMIC))) + frag = skb_unshare(frag, GFP_ATOMIC); + if (unlikely(!frag)) goto err; head = *headbuf = frag; *buf = NULL; |