This is a note to let you know that I've just added the patch titled
nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect
to the 5.4-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:
nfc-fix-null-ptr-dereference-in-llcp_sock_getname-after-failed-connect.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4ac06a1e013cf5fdd963317ffd3b968560f33bba Mon Sep 17 00:00:00 2001
From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>
Date: Mon, 31 May 2021 09:21:38 +0200
Subject: nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect
From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>
commit 4ac06a1e013cf5fdd963317ffd3b968560f33bba upstream.
It's possible to trigger NULL pointer dereference by local unprivileged
user, when calling getsockname() after failed bind() (e.g. the bind
fails because LLCP_SAP_MAX used as SAP):
BUG: kernel NULL pointer dereference, address: 0000000000000000
CPU: 1 PID: 426 Comm: llcp_sock_getna Not tainted 5.13.0-rc2-next-20210521+ #9
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1 04/01/2014
Call Trace:
llcp_sock_getname+0xb1/0xe0
__sys_getpeername+0x95/0xc0
? lockdep_hardirqs_on_prepare+0xd5/0x180
? syscall_enter_from_user_mode+0x1c/0x40
__x64_sys_getpeername+0x11/0x20
do_syscall_64+0x36/0x70
entry_SYSCALL_64_after_hwframe+0x44/0xae
This can be reproduced with Syzkaller C repro (bind followed by
getpeername):
https://syzkaller.appspot.com/x/repro.c?x=14def446e00000
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: d646960f7986 ("NFC: Initial LLCP support")
Reported-by: syzbot+80fb126e7f7d8b1a5914@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: butt3rflyh4ck <butterflyhuangxx@xxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210531072138.5219-1-krzysztof.kozlowski@xxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/nfc/llcp_sock.c | 2 ++
1 file changed, 2 insertions(+)
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -110,6 +110,7 @@ static int llcp_sock_bind(struct socket
if (!llcp_sock->service_name) {
nfc_llcp_local_put(llcp_sock->local);
llcp_sock->local = NULL;
+ llcp_sock->dev = NULL;
ret = -ENOMEM;
goto put_dev;
}
@@ -119,6 +120,7 @@ static int llcp_sock_bind(struct socket
llcp_sock->local = NULL;
kfree(llcp_sock->service_name);
llcp_sock->service_name = NULL;
+ llcp_sock->dev = NULL;
ret = -EADDRINUSE;
goto put_dev;
}
Patches currently in stable-queue which might be from krzysztof.kozlowski@xxxxxxxxxxxxx are
queue-5.4/nfc-fix-null-ptr-dereference-in-llcp_sock_getname-after-failed-connect.patch
