* Re: oops in tcp_v4_rcv. [not found] <3ED54DBC.4020203@colorfullife.com> @ 2003-05-29 1:15 ` Manfred Spraul 2003-05-29 1:40 ` David S. Miller 0 siblings, 1 reply; 6+ messages in thread From: Manfred Spraul @ 2003-05-29 1:15 UTC (permalink / raw) To: David S. Miller; +Cc: netdev, Andrew Morton [netdev added to cc list] I think I understand now what causes the crash: The tcp_ehash assumes that the entries are of the type 'struct inet_sock'. But the actual entry is of the type tcp_tw_bucket. And 'sk->inet.daddr' is not shared between both structures. << net/ipv4/tcp_ipv4, line 510: /* Must check for a TIME_WAIT'er before going to listener hash. */ for (sk = (head + tcp_ehash_size)->chain; sk; sk = sk->next) if (TCP_IPV4_MATCH(sk, acookie, saddr, daddr, ports, dif)) goto hit; << preprocessor output: << for (sk = (head + (tcp_hashinfo.__tcp_ehash_size))->chain; sk; sk = sk->next) if ((((&((struct inet_sock *)sk)->inet)->daddr == (saddr)) && ((&((struct inet_sock *)sk)->inet)->rcv_saddr == (daddr)) && ((*((__u32 *)&((&((struct inet_sock *)sk)->inet)->dport)))== (ports)) && (!((sk)->bound_dev_if) || ((sk)->bound_dev_if == (dif))))) goto hit; << Manfred Spraul wrote: > Hi, > > I'm looking at crashes that occur during network stress testing with > the CONFIG_DEBUG_PAGEALLOC from -mm: Pages that are not in use are > immediately unmapped from the linear mapping, and thus reading stale > pointer causes an immediate oops. > > I've now analyzed one crash: > the oops is in __tcp_v4_lookup_established, in the 2nd look [i.e. > looking at TIME_WAIT sockets. Easy to identify due to the access to > __tcp_ehash_size]. > > The entry in the hash table is an tcp_tw_bucket, and that structure is > only ~88 bytes long. The oops is caused by an access to objp+0x168, > which doesn't exist. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: oops in tcp_v4_rcv. 2003-05-29 1:15 ` oops in tcp_v4_rcv Manfred Spraul @ 2003-05-29 1:40 ` David S. Miller 2003-05-29 1:50 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 6+ messages in thread From: David S. Miller @ 2003-05-29 1:40 UTC (permalink / raw) To: manfred; +Cc: netdev, akpm, acme From: Manfred Spraul <manfred@colorfullife.com> Date: Thu, 29 May 2003 03:15:57 +0200 I think I understand now what causes the crash: The tcp_ehash assumes that the entries are of the type 'struct inet_sock'. But the actual entry is of the type tcp_tw_bucket. And 'sk->inet.daddr' is not shared between both structures. Thanks for figuring this out. Indeed, I had suspected the sock layout change Arnaldo did early in 2.5.x as the main possible suspect. I'll try to fix this. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: oops in tcp_v4_rcv. 2003-05-29 1:40 ` David S. Miller @ 2003-05-29 1:50 ` Arnaldo Carvalho de Melo 2003-05-29 1:51 ` David S. Miller 0 siblings, 1 reply; 6+ messages in thread From: Arnaldo Carvalho de Melo @ 2003-05-29 1:50 UTC (permalink / raw) To: David S. Miller; +Cc: manfred, netdev, akpm Em Wed, May 28, 2003 at 06:40:54PM -0700, David S. Miller escreveu: > From: Manfred Spraul <manfred@colorfullife.com> > Date: Thu, 29 May 2003 03:15:57 +0200 > > I think I understand now what causes the crash: > The tcp_ehash assumes that the entries are of the type 'struct inet_sock'. > But the actual entry is of the type tcp_tw_bucket. And 'sk->inet.daddr' > is not shared between both structures. > > Thanks for figuring this out. Indeed, I had suspected the > sock layout change Arnaldo did early in 2.5.x as the main > possible suspect. > > I'll try to fix this. I'm as well looking at this, longstanding bug :-\ - Arnaldo ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: oops in tcp_v4_rcv. 2003-05-29 1:50 ` Arnaldo Carvalho de Melo @ 2003-05-29 1:51 ` David S. Miller 2003-05-29 2:00 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 6+ messages in thread From: David S. Miller @ 2003-05-29 1:51 UTC (permalink / raw) To: acme; +Cc: manfred, netdev, akpm From: Arnaldo Carvalho de Melo <acme@conectiva.com.br> Date: Wed, 28 May 2003 22:50:20 -0300 Em Wed, May 28, 2003 at 06:40:54PM -0700, David S. Miller escreveu: > I'll try to fix this. I'm as well looking at this, longstanding bug :-\ Here's a patch, should work: --- include/net/tcp.h.~1~ Wed May 28 18:42:52 2003 +++ include/net/tcp.h Wed May 28 18:49:47 2003 @@ -208,6 +208,8 @@ #endif }; +#define tcptw_sk(__sk) ((struct tcp_tw_bucket *)(__sk)) + extern kmem_cache_t *tcp_timewait_cachep; static inline void tcp_tw_put(struct tcp_tw_bucket *tw) @@ -246,7 +248,11 @@ #endif /* __BIG_ENDIAN */ #define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ (((*((__u64 *)&(inet_sk(__sk)->daddr)))== (__cookie)) && \ - ((*((__u32 *)&(inet_sk(__sk)->dport)))== (__ports)) && \ + ((*((__u32 *)&(inet_sk(__sk)->dport)))== (__ports)) && \ + (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) +#define TCP_IPV4_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ + (((*((__u64 *)&(tcptw_sk(__sk)->daddr)))== (__cookie)) && \ + ((*((__u32 *)&(tcptw_sk(__sk)->dport)))== (__ports)) && \ (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) #else /* 32-bit arch */ #define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) @@ -254,6 +260,11 @@ ((inet_sk(__sk)->daddr == (__saddr)) && \ (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ ((*((__u32 *)&(inet_sk(__sk)->dport)))== (__ports)) && \ + (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) +#define TCP_IPV4_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ + ((tcptw_sk(__sk)->daddr == (__saddr)) && \ + (tcptw_sk(__sk)->rcv_saddr == (__daddr)) && \ + ((*((__u32 *)&(tcptw_sk(__sk)->dport)))== (__ports)) && \ (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) #endif /* 64-bit arch */ --- net/ipv4/tcp_ipv4.c.~1~ Wed May 28 18:44:59 2003 +++ net/ipv4/tcp_ipv4.c Wed May 28 18:45:18 2003 @@ -509,7 +509,7 @@ /* Must check for a TIME_WAIT'er before going to listener hash. */ for (sk = (head + tcp_ehash_size)->chain; sk; sk = sk->next) - if (TCP_IPV4_MATCH(sk, acookie, saddr, daddr, ports, dif)) + if (TCP_IPV4_TW_MATCH(sk, acookie, saddr, daddr, ports, dif)) goto hit; out: read_unlock(&head->lock); @@ -570,7 +570,7 @@ skp = &sk2->next) { tw = (struct tcp_tw_bucket *)sk2; - if (TCP_IPV4_MATCH(sk2, acookie, saddr, daddr, ports, dif)) { + if (TCP_IPV4_TW_MATCH(sk2, acookie, saddr, daddr, ports, dif)) { struct tcp_opt *tp = tcp_sk(sk); /* With PAWS, it is safe from the viewpoint ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: oops in tcp_v4_rcv. 2003-05-29 1:51 ` David S. Miller @ 2003-05-29 2:00 ` Arnaldo Carvalho de Melo 2003-05-29 3:06 ` David S. Miller 0 siblings, 1 reply; 6+ messages in thread From: Arnaldo Carvalho de Melo @ 2003-05-29 2:00 UTC (permalink / raw) To: David S. Miller; +Cc: manfred, netdev, akpm Em Wed, May 28, 2003 at 06:51:42PM -0700, David S. Miller escreveu: > From: Arnaldo Carvalho de Melo <acme@conectiva.com.br> > Date: Wed, 28 May 2003 22:50:20 -0300 > > Em Wed, May 28, 2003 at 06:40:54PM -0700, David S. Miller escreveu: > > I'll try to fix this. > > I'm as well looking at this, longstanding bug :-\ > > Here's a patch, should work: At first look, agreed. Thanks David for fixing this. - Arnaldo ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: oops in tcp_v4_rcv. 2003-05-29 2:00 ` Arnaldo Carvalho de Melo @ 2003-05-29 3:06 ` David S. Miller 0 siblings, 0 replies; 6+ messages in thread From: David S. Miller @ 2003-05-29 3:06 UTC (permalink / raw) To: acme; +Cc: manfred, netdev, akpm From: Arnaldo Carvalho de Melo <acme@conectiva.com.br> Date: Wed, 28 May 2003 23:00:35 -0300 Em Wed, May 28, 2003 at 06:51:42PM -0700, David S. Miller escreveu: > Here's a patch, should work: At first look, agreed. Thanks David for fixing this. No problem. And a big double-thanks for Mandred for tracking this down. I wish him luck in tracking down the task struct use-after-free that he's also seeing. :-) ^ permalink raw reply [flat|nested] 6+ messages in thread
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[not found] <3ED54DBC.4020203@colorfullife.com>
2003-05-29 1:15 ` oops in tcp_v4_rcv Manfred Spraul
2003-05-29 1:40 ` David S. Miller
2003-05-29 1:50 ` Arnaldo Carvalho de Melo
2003-05-29 1:51 ` David S. Miller
2003-05-29 2:00 ` Arnaldo Carvalho de Melo
2003-05-29 3:06 ` David S. Miller
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