diff options
| author | Eric Dumazet <edumazet@google.com> | 2016-08-17 05:56:26 -0700 |
|---|---|---|
| committer | Winnie Hsu <whsu@nvidia.com> | 2018-04-19 10:55:59 -0700 |
| commit | ab6caaa6ab10ff7e3c6d536277dacf1e644c3cd2 (patch) | |
| tree | 97224738dd2c5fd4028120828d1f7b38372cf061 /include | |
| parent | ff6dbd5dff104b4d6d4aeeeafe90493e377474e2 (diff) | |
tcp: fix use after free in tcp_xmit_retransmit_queue()
When tcp_sendmsg() allocates a fresh and empty skb, it puts it
at the tail of the write queue using tcp_add_write_queue_tail()
Then it attempts to copy user data into this fresh skb.
If the copy fails, we undo the work and remove the fresh skb.
Unfortunately, this undo lacks the change done to tp->highest_sack and we can leave a dangling pointer (to a freed skb)
Later, tcp_xmit_retransmit_queue() can dereference this pointer and
access freed memory. For regular kernels where memory is not unmapped,
this might cause SACK bugs because tcp_highest_sack_seq() is buggy,
returning garbage instead of tp->snd_nxt, but with various debug
features like CONFIG_DEBUG_PAGEALLOC, this can crash the kernel.
This bug was found by Marco Grassi thanks to syzkaller.
Bug 1823317
Bug 1935735
Change-Id: I9bf709b21e5637f338c34d894617f33d84f93ecc
Reported-by: Marco Grassi <marco.gra@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Gagan Grover <ggrover@nvidia.com>
Reviewed-on: http://git-master/r/1260003
(cherry picked from commit 0c20962647685008dfc6a15fb8a2169ed2abafe6)
Reviewed-on: https://git-master.nvidia.com/r/1690290
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Tested-by: Amulya Yarlagadda <ayarlagadda@nvidia.com>
Reviewed-by: Winnie Hsu <whsu@nvidia.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/tcp.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 13f12c10f03b..013daf1494ba 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1392,6 +1392,8 @@ static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unli { if (sk->sk_send_head == skb_unlinked) sk->sk_send_head = NULL; + if (tcp_sk(sk)->highest_sack == skb_unlinked) + tcp_sk(sk)->highest_sack = NULL; } static inline void tcp_init_send_head(struct sock *sk) |