* [PATCH] /proc/net/tcp + ipv6 hang
@ 2002-12-23 1:57 Anders Gustafsson
2002-12-23 2:03 ` Arnaldo Carvalho de Melo
2002-12-23 2:40 ` Arnaldo Carvalho de Melo
0 siblings, 2 replies; 6+ messages in thread
From: Anders Gustafsson @ 2002-12-23 1:57 UTC (permalink / raw)
To: David S. Miller; +Cc: linux-kernel, joe user, Arnaldo Carvalho de Melo
Hi,
this patch fixes an infinite loop when reading /proc/net/tcp and having
daemons listening on ipv6.
--
Anders Gustafsson - andersg@0x63.nu - http://0x63.nu/
You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.
===================================================================
ChangeSet@1.913, 2002-12-23 02:49:19+01:00, andersg@0x63.nu
Fix infinite loop when reading /proc/net/tcp with ipv6-sockets.
tcp_ipv4.c | 1 +
1 files changed, 1 insertion(+)
diff -Nru a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
--- a/net/ipv4/tcp_ipv4.c Mon Dec 23 02:55:45 2002
+++ b/net/ipv4/tcp_ipv4.c Mon Dec 23 02:55:45 2002
@@ -2236,6 +2236,7 @@
goto get_req;
}
read_unlock_bh(&tp->syn_wait_lock);
+ sk = sk->next;
}
if (++st->bucket < TCP_LHTABLE_SIZE) {
sk = tcp_listening_hash[st->bucket];
===================================================================
This BitKeeper patch contains the following changesets:
1.913
## Wrapped with gzip_uu ##
begin 664 bkpatch1524
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M2)&/\2B:)Y)?EL^KL3*EUS31UI!VS?98+)QWSR/&6!X0QWQ(\BS%H[!$]DA7
MXC_4U1\*OL.HVQVGU\GT*39>(;<OGN@,D`5!WT()?3NZ,K1W;^Z_$UV3;OO;
1=4D9*2FJ!?L-758XOZ\$````
`
end
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] /proc/net/tcp + ipv6 hang 2002-12-23 1:57 [PATCH] /proc/net/tcp + ipv6 hang Anders Gustafsson @ 2002-12-23 2:03 ` Arnaldo Carvalho de Melo 2002-12-23 2:40 ` Arnaldo Carvalho de Melo 1 sibling, 0 replies; 6+ messages in thread From: Arnaldo Carvalho de Melo @ 2002-12-23 2:03 UTC (permalink / raw) To: Anders Gustafsson; +Cc: David S. Miller, linux-kernel, joe user Em Mon, Dec 23, 2002 at 02:57:23AM +0100, Anders Gustafsson escreveu: > Hi, > > this patch fixes an infinite loop when reading /proc/net/tcp and having > daemons listening on ipv6. I'm checking your patch, just received the message, but thanks a lot for doing this! - Arnaldo ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] /proc/net/tcp + ipv6 hang 2002-12-23 1:57 [PATCH] /proc/net/tcp + ipv6 hang Anders Gustafsson 2002-12-23 2:03 ` Arnaldo Carvalho de Melo @ 2002-12-23 2:40 ` Arnaldo Carvalho de Melo 2002-12-23 3:08 ` Anders Gustafsson 2002-12-23 7:20 ` David S. Miller 1 sibling, 2 replies; 6+ messages in thread From: Arnaldo Carvalho de Melo @ 2002-12-23 2:40 UTC (permalink / raw) To: Anders Gustafsson; +Cc: David S. Miller, linux-kernel, joe user Em Mon, Dec 23, 2002 at 02:57:23AM +0100, Anders Gustafsson escreveu: > this patch fixes an infinite loop when reading /proc/net/tcp and having > daemons listening on ipv6. Perfect! Thanks for the fix, looking at it now it seems soooo obvious, /me slaps himself in the face 8) David, pleasey apply, I think there is still at least one bug with this code, will be testing this as soon as possible. Anders, if you're feeling brave, from the top of my head, think about what happens if somebody only reads the first, say, 10 bytes of /proc/net/tcp, will we unlocking a not held lock at tcp_seq_stop, no? :-) Another fix for this one will be apreciated 8) - Arnaldo ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] /proc/net/tcp + ipv6 hang 2002-12-23 2:40 ` Arnaldo Carvalho de Melo @ 2002-12-23 3:08 ` Anders Gustafsson 2002-12-23 3:27 ` Arnaldo Carvalho de Melo 2002-12-23 7:20 ` David S. Miller 1 sibling, 1 reply; 6+ messages in thread From: Anders Gustafsson @ 2002-12-23 3:08 UTC (permalink / raw) To: Arnaldo Carvalho de Melo; +Cc: David S. Miller, linux-kernel On Mon, Dec 23, 2002 at 12:40:17AM -0200, Arnaldo Carvalho de Melo wrote: > > Anders, if you're feeling brave, from the top of my head, think about what > happens if somebody only reads the first, say, 10 bytes of /proc/net/tcp, will > we unlocking a not held lock at tcp_seq_stop, no? :-) Yes, I was just looking into the locking... But it's rather messy with locks between calls and goto's and I think I'd better get some sleep before saying anything for certain. Is there any reason holding the lock between listening_get_first() and the first call to listening_get_next(), but not between consecutive calls to listening_get_next()? Otherwise we could just always release the lock in listening_get_first. (All this applies to established_get_first/next too.) OOPS, I just realizes we might be talking about different locks :) I was talking about read_[un]lock_bh(&tp->syn_wait_lock); in listening_get_first/next What lock are you talking about? As far as I can see, in TCP_SEQ_STATE_OPENREQ tp->syn_wait_lock is always held and in TCP_SEQ_STATE_LISTENING the tcp_listen_lock and so on? -- Anders Gustafsson - andersg@0x63.nu - http://0x63.nu/ ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] /proc/net/tcp + ipv6 hang 2002-12-23 3:08 ` Anders Gustafsson @ 2002-12-23 3:27 ` Arnaldo Carvalho de Melo 0 siblings, 0 replies; 6+ messages in thread From: Arnaldo Carvalho de Melo @ 2002-12-23 3:27 UTC (permalink / raw) To: Anders Gustafsson; +Cc: David S. Miller, linux-kernel Em Mon, Dec 23, 2002 at 04:08:12AM +0100, Anders Gustafsson escreveu: > On Mon, Dec 23, 2002 at 12:40:17AM -0200, Arnaldo Carvalho de Melo wrote: > > Anders, if you're feeling brave, from the top of my head, think about what > > happens if somebody only reads the first, say, 10 bytes of /proc/net/tcp, > > will we unlocking a not held lock at tcp_seq_stop, no? :-) > Yes, I was just looking into the locking... But it's rather messy with locks > between calls and goto's and I think I'd better get some sleep before saying > anything for certain. Is there any reason holding the lock between > listening_get_first() and the first call to listening_get_next(), but not > between consecutive calls to listening_get_next()? Otherwise we could just > always release the lock in listening_get_first. > (All this applies to established_get_first/next too.) We have to hold the lock (tp->syn_wait_lock) because in listening_get_first we return one of the elements of the list guarded by tp->syn_wait_lock, so we have to make sure that it doesn't disappears under our feet when we go to the next one in listening_get_next > OOPS, I just realizes we might be talking about different locks :) different problem :-) > I was talking about > read_[un]lock_bh(&tp->syn_wait_lock); in listening_get_first/next > What lock are you talking about? > As far as I can see, in TCP_SEQ_STATE_OPENREQ tp->syn_wait_lock is always > held and in TCP_SEQ_STATE_LISTENING the tcp_listen_lock and so on? Notice that we call tcp_listen_lock() only in tcp_get_idx, and tcp_get_idx is not called for the first record, that is the header of /proc/net/tcp, we're in TCP_SEQ_STATE_LISTENING that is zero (we zeroed the private seq_file area in tcp_seq_open, so if the userlevel program only asks for, say, four bytes (like midnight commander's editor, to read the magic number for the file to decide which viewer is associated with the type indicated by the magic number) this will be satisfied with just one call to tcp_seq_show, i.e. only when tcp_seq_start returns (void *), without calling tcp_get_idx to call tcp_listen_lock(). b00m, we drop a lock not held, got it? - Arnaldo ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] /proc/net/tcp + ipv6 hang 2002-12-23 2:40 ` Arnaldo Carvalho de Melo 2002-12-23 3:08 ` Anders Gustafsson @ 2002-12-23 7:20 ` David S. Miller 1 sibling, 0 replies; 6+ messages in thread From: David S. Miller @ 2002-12-23 7:20 UTC (permalink / raw) To: acme; +Cc: andersg, linux-kernel, joe_user35 From: Arnaldo Carvalho de Melo <acme@conectiva.com.br> Date: Mon, 23 Dec 2002 00:40:17 -0200 David, pleasey apply, I think there is still at least one bug with this code, will be testing this as soon as possible. Done, thanks. ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2002-12-23 7:18 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2002-12-23 1:57 [PATCH] /proc/net/tcp + ipv6 hang Anders Gustafsson 2002-12-23 2:03 ` Arnaldo Carvalho de Melo 2002-12-23 2:40 ` Arnaldo Carvalho de Melo 2002-12-23 3:08 ` Anders Gustafsson 2002-12-23 3:27 ` Arnaldo Carvalho de Melo 2002-12-23 7:20 ` David S. Miller
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