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Message-Id: <20210608175933.371462446@linuxfoundation.org>
Date: Tue, 8 Jun 2021 20:27:14 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
syzbot+80fb126e7f7d8b1a5914@...kaller.appspotmail.com,
butt3rflyh4ck <butterflyhuangxx@...il.com>,
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 4.19 33/58] nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect
From: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
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@...r.kernel.org>
Fixes: d646960f7986 ("NFC: Initial LLCP support")
Reported-by: syzbot+80fb126e7f7d8b1a5914@...kaller.appspotmail.com
Reported-by: butt3rflyh4ck <butterflyhuangxx@...il.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Link: https://lore.kernel.org/r/20210531072138.5219-1-krzysztof.kozlowski@canonical.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/nfc/llcp_sock.c | 2 ++
1 file changed, 2 insertions(+)
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -122,6 +122,7 @@ 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;
}
@@ -131,6 +132,7 @@ 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;
}
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