Re: Patch "net: kcm: fix memory leak in kcm_sendmsg" has been added to the 5.12-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 08, 2021 at 03:41:59PM +0300, Pavel Skripkin wrote:
> On Tue, 08 Jun 2021 14:32:23 +0200
> <gregkh@linuxfoundation.org> wrote:
> 
> > 
> > This is a note to let you know that I've just added the patch titled
> > 
> >     net: kcm: fix memory leak in kcm_sendmsg
> > 
> > to the 5.12-stable tree which can be found at:
> >     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> > 
> > The filename of the patch is:
> >      net-kcm-fix-memory-leak-in-kcm_sendmsg.patch
> > and it can be found in the queue-5.12 subdirectory.
> > 
> > If you, or anyone else, feels it should not be added to the stable
> > tree, please let <stable@vger.kernel.org> know about it.
> > 
> > 
> > From c47cc304990a2813995b1a92bbc11d0bb9a19ea9 Mon Sep 17 00:00:00 2001
> > From: Pavel Skripkin <paskripkin@gmail.com>
> > Date: Wed, 2 Jun 2021 22:26:40 +0300
> > Subject: net: kcm: fix memory leak in kcm_sendmsg
> > 
> > From: Pavel Skripkin <paskripkin@gmail.com>
> > 
> > commit c47cc304990a2813995b1a92bbc11d0bb9a19ea9 upstream.
> > 
> > Syzbot reported memory leak in kcm_sendmsg()[1].
> > The problem was in non-freed frag_list in case of error.
> > 
> > In the while loop:
> > 
> > 	if (head == skb)
> > 		skb_shinfo(head)->frag_list = tskb;
> > 	else
> > 		skb->next = tskb;
> > 
> > frag_list filled with skbs, but nothing was freeing them.
> > 
> > backtrace:
> >   [<0000000094c02615>] __alloc_skb+0x5e/0x250 net/core/skbuff.c:198
> >   [<00000000e5386cbd>] alloc_skb include/linux/skbuff.h:1083 [inline]
> >   [<00000000e5386cbd>] kcm_sendmsg+0x3b6/0xa50 net/kcm/kcmsock.c:967
> > [1] [<00000000f1613a8a>] sock_sendmsg_nosec net/socket.c:652 [inline]
> >   [<00000000f1613a8a>] sock_sendmsg+0x4c/0x60 net/socket.c:672
> > 
> > Reported-and-tested-by:
> > syzbot+b039f5699bd82e1fb011@syzkaller.appspotmail.com Fixes:
> > ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module") Cc:
> > stable@vger.kernel.org Signed-off-by: Pavel Skripkin
> > <paskripkin@gmail.com> Signed-off-by: David S. Miller
> > <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> ---
> >  net/kcm/kcmsock.c |    5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> 
> Hi, Greg!
> 
> I CCed stable. This patch is broken and I've already sent a revert for
> this.
> 
> https://git.kernel.org/netdev/net/c/a47c397bb29f
> 
> Please, don't add this to stable trees. Im sorry

Now dropped from everywhere, thanks for letting me know.

greg k-h