Re: Patch "net: kcm: fix memory leak in kcm_sendmsg" has been added to the 4.14-stable tree

[Pavel Skripkin <paskripkin@gmail.com>]

On Tue, 08 Jun 2021 14:30:53 +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 4.14-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-4.14 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


With regards,
Pavel Skripkin