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authorKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>2021-05-31 10:21:38 +0300
committerJakub Kicinski <kuba@kernel.org>2021-06-01 08:43:27 +0300
commit4ac06a1e013cf5fdd963317ffd3b968560f33bba (patch)
tree6638f0737d4f08a02e7ced318ca8c8706352cb56
parent593f555fbc6091bbaec8dd2a38b47ee643412e61 (diff)
downloadlinux-4ac06a1e013cf5fdd963317ffd3b968560f33bba.tar.xz
nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect
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@vger.kernel.org> Fixes: d646960f7986 ("NFC: Initial LLCP support") Reported-by: syzbot+80fb126e7f7d8b1a5914@syzkaller.appspotmail.com Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Link: https://lore.kernel.org/r/20210531072138.5219-1-krzysztof.kozlowski@canonical.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--net/nfc/llcp_sock.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 53dbe733f998..6cfd30fc0798 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -110,6 +110,7 @@ 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;
}
@@ -119,6 +120,7 @@ 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;
}