From 9dcbc313cd4ada386487b3055d9b6ec169d51765 Mon Sep 17 00:00:00 2001 From: Ezequiel Garcia Date: Thu, 29 Dec 2016 09:51:19 -0300 Subject: Bluetooth: Fix NULL pointer dereference in bt_sock_recvmsg As per the comment in include/linux/net.h, the recvfrom handlers should expect msg_name to be NULL. However, bt_sock_recvmsg() is currently not checking it, which could lead to a NULL pointer dereference. The following NULL pointer dereference was produced while testing L2CAP datagram reception. Note that the kernel is tainted due to the r8723bs module being inserted. However, it seems the fix still applies. $ l2test -r -G l2test[326]: Receiving ... Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = ee008000 [00000000] *pgd=7f896835 Internal error: Oops: 817 [#1] PREEMPT SMP ARM Modules linked in: r8723bs(O) CPU: 0 PID: 326 Comm: l2test Tainted: G O 4.8.0 #1 Hardware name: Allwinner sun7i (A20) Family task: ef1c6880 task.stack: eea70000 PC is at __memzero+0x58/0x80 LR is at l2cap_skb_msg_name+0x1c/0x4c pc : [] lr : [] psr: 00070013 sp : eea71e60 ip : 00000000 fp : 00034e1c r10: 00000000 r9 : 00000000 r8 : eea71ed4 r7 : 000002a0 r6 : eea71ed8 r5 : 00000000 r4 : ee4a5d80 r3 : 00000000 r2 : 00000000 r1 : 0000000e r0 : 00000000 Flags: nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: 7600806a DAC: 00000051 Process l2test (pid: 326, stack limit = 0xeea70210) Stack: (0xeea71e60 to 0xeea72000) 1e60: ee4a5d80 eeac2800 000002a0 c04d7114 173eefa0 00000000 c06ca68e 00000000 1e80: 00000001 eeac2800 eef23500 00000000 000002a0 eea71ed4 eea70000 c0504d50 1ea0: 00000000 00000000 eef23500 00000000 00000000 c044e8a0 eea71edc eea9f904 1ec0: bef89aa0 fffffff7 00000000 00035008 000002a0 00000000 00000000 00000000 1ee0: 00000000 00000000 eea71ed4 00000000 00000000 00000000 00004000 00000000 1f00: 0000011b c01078c4 eea70000 c044e5e4 00000000 00000000 642f0001 6c2f7665 1f20: 0000676f 00000000 00000000 00000000 00000000 00000000 00000000 00000000 1f40: 00000000 00000000 00000000 00000000 00000000 ffffffff 00000001 bef89ad8 1f60: 000000a8 c01078c4 eea70000 00000000 00034e1c c01e6c74 00000000 00000000 1f80: 00034e1c 000341f8 00000000 00000123 c01078c4 c044e90c 00000000 00000000 1fa0: 000002a0 c0107700 00034e1c 000341f8 00000003 00035008 000002a0 00000000 1fc0: 00034e1c 000341f8 00000000 00000123 00000000 00000000 00011ffc 00034e1c 1fe0: 00000000 bef89aa4 0001211c b6eebb60 60070010 00000003 00000000 00000000 [] (__memzero) from [] (l2cap_skb_msg_name+0x1c/0x4c) [] (l2cap_skb_msg_name) from [] (bt_sock_recvmsg+0x128/0x160) [] (bt_sock_recvmsg) from [] (l2cap_sock_recvmsg+0x98/0x134) [] (l2cap_sock_recvmsg) from [] (SyS_recvfrom+0x94/0xec) [] (SyS_recvfrom) from [] (SyS_recv+0x14/0x1c) [] (SyS_recv) from [] (ret_fast_syscall+0x0/0x3c) Code: e3110010 18a0500c e49de004 e3110008 (18a0000c) ---[ end trace 224e35e79fe06b42 ]--- Signed-off-by: Ezequiel Garcia Signed-off-by: Marcel Holtmann --- net/bluetooth/af_bluetooth.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/bluetooth/af_bluetooth.c') diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index 1aff2da9bc74..cfb2faba46de 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -245,7 +245,7 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, if (err == 0) { sock_recv_ts_and_drops(msg, sk, skb); - if (bt_sk(sk)->skb_msg_name) + if (msg->msg_name && bt_sk(sk)->skb_msg_name) bt_sk(sk)->skb_msg_name(skb, msg->msg_name, &msg->msg_namelen); } -- cgit v1.2.1