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authorIlpo Järvinen2009-05-10 20:32:34 +0000
committerDavid S. Miller2009-05-18 15:05:40 -0700
commit775273131810caa41dfc7f9e552ea5d8508caf40 (patch)
tree38ee8e4815d614c483be352524134c6f7fc163c3
parent705efc3b03cbee449e4d83b230423894152f7982 (diff)
tcp: fix MSG_PEEK race check
Commit 518a09ef11 (tcp: Fix recvmsg MSG_PEEK influence of blocking behavior) lets the loop run longer than the race check did previously expect, so we need to be more careful with this check and consider the work we have been doing. I tried my best to deal with urg hole madness too which happens here: if (!sock_flag(sk, SOCK_URGINLINE)) { ++*seq; ... by using additional offset by one but I certainly have very little interest in testing that part. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Tested-by: Frans Pop <elendil@planet.nl> Tested-by: Ian Zimmermann <itz@buug.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1d7f49c6f0ca..7a0f0b27bf1f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1321,6 +1321,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
struct task_struct *user_recv = NULL;
int copied_early = 0;
struct sk_buff *skb;
+ u32 urg_hole = 0;
lock_sock(sk);
@@ -1532,7 +1533,8 @@ do_prequeue:
}
}
}
- if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
+ if ((flags & MSG_PEEK) &&
+ (peek_seq - copied - urg_hole != tp->copied_seq)) {
if (net_ratelimit())
printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
current->comm, task_pid_nr(current));
@@ -1553,6 +1555,7 @@ do_prequeue:
if (!urg_offset) {
if (!sock_flag(sk, SOCK_URGINLINE)) {
++*seq;
+ urg_hole++;
offset++;
used--;
if (!used)