* [PATCH] tun: don't zeroize sock->file on detach @ 2012-08-09 12:50 Stanislav Kinsbursky 2012-08-09 23:16 ` David Miller 0 siblings, 1 reply; 5+ messages in thread From: Stanislav Kinsbursky @ 2012-08-09 12:50 UTC (permalink / raw) To: davem; +Cc: dhowells, netdev, rick.jones2, ycheng, linux-kernel This is a fix for bug, introduced in 3.4 kernel by commit 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d, which, among other things, replaced simple sock_put() by sk_release_kernel(). Below is sequence, which leads to oops for non-persistent devices: tun_chr_close() tun_detach() <== tun->socket.file = NULL tun_free_netdev() sk_release_sock() sock_release(sock->file == NULL) iput(SOCK_INODE(sock)) <== dereference on NULL pointer This patch just removes zeroing of socket's file from __tun_detach(). sock_release() will do this. Cc: stable@vger.kernel.org Reported-by: Ruan Zhijie <ruanzhijie@hotmail.com> Tested-by: Ruan Zhijie <ruanzhijie@hotmail.com> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> --- drivers/net/tun.c | 1 - 1 files changed, 0 insertions(+), 1 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 987aeef..c1639f3 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -185,7 +185,6 @@ static void __tun_detach(struct tun_struct *tun) netif_tx_lock_bh(tun->dev); netif_carrier_off(tun->dev); tun->tfile = NULL; - tun->socket.file = NULL; netif_tx_unlock_bh(tun->dev); /* Drop read queue */ ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: don't zeroize sock->file on detach 2012-08-09 12:50 [PATCH] tun: don't zeroize sock->file on detach Stanislav Kinsbursky @ 2012-08-09 23:16 ` David Miller 2012-08-21 16:04 ` Stanislav Kinsbursky 0 siblings, 1 reply; 5+ messages in thread From: David Miller @ 2012-08-09 23:16 UTC (permalink / raw) To: skinsbursky; +Cc: dhowells, netdev, rick.jones2, ycheng, linux-kernel From: Stanislav Kinsbursky <skinsbursky@parallels.com> Date: Thu, 09 Aug 2012 16:50:40 +0400 > This is a fix for bug, introduced in 3.4 kernel by commit > 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d, which, among other things, replaced > simple sock_put() by sk_release_kernel(). Below is sequence, which leads to > oops for non-persistent devices: > > tun_chr_close() > tun_detach() <== tun->socket.file = NULL > tun_free_netdev() > sk_release_sock() > sock_release(sock->file == NULL) > iput(SOCK_INODE(sock)) <== dereference on NULL pointer > > This patch just removes zeroing of socket's file from __tun_detach(). > sock_release() will do this. > > Cc: stable@vger.kernel.org > Reported-by: Ruan Zhijie <ruanzhijie@hotmail.com> > Tested-by: Ruan Zhijie <ruanzhijie@hotmail.com> > Acked-by: Al Viro <viro@ZenIV.linux.org.uk> > Acked-by: Eric Dumazet <edumazet@google.com> > Acked-by: Yuchung Cheng <ycheng@google.com> > Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Applied, thanks. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: don't zeroize sock->file on detach 2012-08-09 23:16 ` David Miller @ 2012-08-21 16:04 ` Stanislav Kinsbursky 2012-08-21 17:18 ` Neal Cardwell 0 siblings, 1 reply; 5+ messages in thread From: Stanislav Kinsbursky @ 2012-08-21 16:04 UTC (permalink / raw) To: David Miller; +Cc: dhowells, netdev, rick.jones2, ycheng, linux-kernel, mikulas 10.08.2012 03:16, David Miller пишет: > From: Stanislav Kinsbursky <skinsbursky@parallels.com> > Date: Thu, 09 Aug 2012 16:50:40 +0400 > >> This is a fix for bug, introduced in 3.4 kernel by commit >> 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d, which, among other things, replaced >> simple sock_put() by sk_release_kernel(). Below is sequence, which leads to >> oops for non-persistent devices: >> >> tun_chr_close() >> tun_detach() <== tun->socket.file = NULL >> tun_free_netdev() >> sk_release_sock() >> sock_release(sock->file == NULL) >> iput(SOCK_INODE(sock)) <== dereference on NULL pointer >> >> This patch just removes zeroing of socket's file from __tun_detach(). >> sock_release() will do this. >> >> Cc: stable@vger.kernel.org >> Reported-by: Ruan Zhijie <ruanzhijie@hotmail.com> >> Tested-by: Ruan Zhijie <ruanzhijie@hotmail.com> >> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> >> Acked-by: Eric Dumazet <edumazet@google.com> >> Acked-by: Yuchung Cheng <ycheng@google.com> >> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> > > Applied, thanks. > Hi, David. I found out, that this commit: b09e786bd1dd66418b69348cb110f3a64764626a was previous attempt to fix the problem. I believe this commit have to be dropped. -- Best regards, Stanislav Kinsbursky ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: don't zeroize sock->file on detach 2012-08-21 16:04 ` Stanislav Kinsbursky @ 2012-08-21 17:18 ` Neal Cardwell 2012-08-22 9:14 ` Stanislav Kinsbursky 0 siblings, 1 reply; 5+ messages in thread From: Neal Cardwell @ 2012-08-21 17:18 UTC (permalink / raw) To: Stanislav Kinsbursky Cc: David Miller, dhowells, netdev, rick.jones2, ycheng, linux-kernel, mikulas On Tue, Aug 21, 2012 at 12:04 PM, Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: > 10.08.2012 03:16, David Miller пишет: > >> From: Stanislav Kinsbursky <skinsbursky@parallels.com> >> Date: Thu, 09 Aug 2012 16:50:40 +0400 >> >>> This is a fix for bug, introduced in 3.4 kernel by commit >>> 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d, which, among other things, >>> replaced >>> simple sock_put() by sk_release_kernel(). Below is sequence, which leads >>> to >>> oops for non-persistent devices: >>> >>> tun_chr_close() >>> tun_detach() <== tun->socket.file = NULL >>> tun_free_netdev() >>> sk_release_sock() >>> sock_release(sock->file == NULL) >>> iput(SOCK_INODE(sock)) <== dereference on NULL pointer >>> >>> This patch just removes zeroing of socket's file from __tun_detach(). >>> sock_release() will do this. >>> >>> Cc: stable@vger.kernel.org >>> Reported-by: Ruan Zhijie <ruanzhijie@hotmail.com> >>> Tested-by: Ruan Zhijie <ruanzhijie@hotmail.com> >>> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> >>> Acked-by: Eric Dumazet <edumazet@google.com> >>> Acked-by: Yuchung Cheng <ycheng@google.com> >>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >> >> >> Applied, thanks. >> > > Hi, David. > I found out, that this commit: b09e786bd1dd66418b69348cb110f3a64764626a > was previous attempt to fix the problem. > I believe this commit have to be dropped. Have you tried testing with that commit reverted? AFAICT from reading the code, if you revert b09e786bd1dd66418b69348cb110f3a64764626a then the sockets_in_use count becomes incorrect, because sock_release() will be calling this_cpu_sub() for each tun socket teardown when there was no corresponding this_cpu_add() for the tun socket (because the tun socket is not allocated with sock_alloc()). Can you sketch in more detail why that commit should be dropped? neal ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: don't zeroize sock->file on detach 2012-08-21 17:18 ` Neal Cardwell @ 2012-08-22 9:14 ` Stanislav Kinsbursky 0 siblings, 0 replies; 5+ messages in thread From: Stanislav Kinsbursky @ 2012-08-22 9:14 UTC (permalink / raw) To: Neal Cardwell Cc: David Miller, dhowells, netdev, rick.jones2, ycheng, linux-kernel, mikulas 21.08.2012 21:18, Neal Cardwell пишет: > On Tue, Aug 21, 2012 at 12:04 PM, Stanislav Kinsbursky > <skinsbursky@parallels.com> wrote: >> 10.08.2012 03:16, David Miller пишет: >> >>> From: Stanislav Kinsbursky <skinsbursky@parallels.com> >>> Date: Thu, 09 Aug 2012 16:50:40 +0400 >>> >>>> This is a fix for bug, introduced in 3.4 kernel by commit >>>> 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d, which, among other things, >>>> replaced >>>> simple sock_put() by sk_release_kernel(). Below is sequence, which leads >>>> to >>>> oops for non-persistent devices: >>>> >>>> tun_chr_close() >>>> tun_detach() <== tun->socket.file = NULL >>>> tun_free_netdev() >>>> sk_release_sock() >>>> sock_release(sock->file == NULL) >>>> iput(SOCK_INODE(sock)) <== dereference on NULL pointer >>>> >>>> This patch just removes zeroing of socket's file from __tun_detach(). >>>> sock_release() will do this. >>>> >>>> Cc: stable@vger.kernel.org >>>> Reported-by: Ruan Zhijie <ruanzhijie@hotmail.com> >>>> Tested-by: Ruan Zhijie <ruanzhijie@hotmail.com> >>>> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> >>>> Acked-by: Eric Dumazet <edumazet@google.com> >>>> Acked-by: Yuchung Cheng <ycheng@google.com> >>>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >>> >>> >>> Applied, thanks. >>> >> >> Hi, David. >> I found out, that this commit: b09e786bd1dd66418b69348cb110f3a64764626a >> was previous attempt to fix the problem. >> I believe this commit have to be dropped. > > Have you tried testing with that commit reverted? AFAICT from reading > the code, if you revert b09e786bd1dd66418b69348cb110f3a64764626a then > the sockets_in_use count becomes incorrect, because sock_release() > will be calling this_cpu_sub() for each tun socket teardown when there > was no corresponding this_cpu_add() for the tun socket (because the > tun socket is not allocated with sock_alloc()). > > Can you sketch in more detail why that commit should be dropped? > Yep, I've noticed, that first commit patch fixes two problems simultaneously. Here are they: 1) Dereference of invalid SOCK_INODE() 2) sockets_in_use incorrect value. But I believe, that introducing new SOCK_EXTERNALLY_ALLOCATED socket flag and use it in generic code just to handle tun issues is overkill. My patch solves first problem mush simpler, than mentioned commit. About second problem... What about this: diff --git a/net/socket.c b/net/socket.c index dfe5b66..dab462b 100644 --- a/net/socket.c +++ b/net/socket.c @@ -526,8 +526,8 @@ void sock_release(struct socket *sock) if (test_bit(SOCK_EXTERNALLY_ALLOCATED, &sock->flags)) return; - this_cpu_sub(sockets_in_use, 1); if (!sock->file) { + this_cpu_sub(sockets_in_use, 1); iput(SOCK_INODE(sock)); return; } ? > neal > -- Best regards, Stanislav Kinsbursky ^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-08-22 9:14 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-08-09 12:50 [PATCH] tun: don't zeroize sock->file on detach Stanislav Kinsbursky 2012-08-09 23:16 ` David Miller 2012-08-21 16:04 ` Stanislav Kinsbursky 2012-08-21 17:18 ` Neal Cardwell 2012-08-22 9:14 ` Stanislav Kinsbursky
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