From: Krzysztof Kozlowski
stable inclusion
from linux-4.19.194
commit 93e4ac2a9979a9a4ecc158409ed9c3044dc0ae1f
category: bugfix
issue: #I421HG
CVE: CVE-2021-3587
--------------------------------
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:
Fixes: d646960f7986 ("NFC: Initial LLCP support")
Reported-by: syzbot+80fb126e7f7d8b1a5914@syzkaller.appspotmail.com
Reported-by: butt3rflyh4ck
Signed-off-by: Krzysztof Kozlowski
Link: https://lore.kernel.org/r/20210531072138.5219-1-krzysztof.kozlowski@canonica...
Signed-off-by: Jakub Kicinski
Signed-off-by: Greg Kroah-Hartman
Signed-off-by: Yang Yingliang
Signed-off-by: Yu Changchun
---
net/nfc/llcp_sock.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 59de4f54d..23f7116d1 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -122,6 +122,7 @@ static int llcp_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
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 *sock, struct sockaddr *addr, int alen)
llcp_sock->local = NULL;
kfree(llcp_sock->service_name);
llcp_sock->service_name = NULL;
+ llcp_sock->dev = NULL;
ret = -EADDRINUSE;
goto put_dev;
}
--
2.25.1
