netdev - [PATCH net] nfc: fix memory leak in llcp_sock

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Message-Id: <20191004180834.108250-1-edumazet@google.com>
Date:   Fri,  4 Oct 2019 11:08:34 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net] nfc: fix memory leak in llcp_sock_bind()

sysbot reported a memory leak after a bind() has failed.

While we are at it, abort the operation if kmemdup() has failed.

BUG: memory leak
unreferenced object 0xffff888105d83ec0 (size 32):
  comm "syz-executor067", pid 7207, jiffies 4294956228 (age 19.430s)
  hex dump (first 32 bytes):
    00 69 6c 65 20 72 65 61 64 00 6e 65 74 3a 5b 34  .ile read.net:[4
    30 32 36 35 33 33 30 39 37 5d 00 00 00 00 00 00  026533097]......
  backtrace:
    [<0000000036bac473>] kmemleak_alloc_recursive /./include/linux/kmemleak.h:43 [inline]
    [<0000000036bac473>] slab_post_alloc_hook /mm/slab.h:522 [inline]
    [<0000000036bac473>] slab_alloc /mm/slab.c:3319 [inline]
    [<0000000036bac473>] __do_kmalloc /mm/slab.c:3653 [inline]
    [<0000000036bac473>] __kmalloc_track_caller+0x169/0x2d0 /mm/slab.c:3670
    [<000000000cd39d07>] kmemdup+0x27/0x60 /mm/util.c:120
    [<000000008e57e5fc>] kmemdup /./include/linux/string.h:432 [inline]
    [<000000008e57e5fc>] llcp_sock_bind+0x1b3/0x230 /net/nfc/llcp_sock.c:107
    [<000000009cb0b5d3>] __sys_bind+0x11c/0x140 /net/socket.c:1647
    [<00000000492c3bbc>] __do_sys_bind /net/socket.c:1658 [inline]
    [<00000000492c3bbc>] __se_sys_bind /net/socket.c:1656 [inline]
    [<00000000492c3bbc>] __x64_sys_bind+0x1e/0x30 /net/socket.c:1656
    [<0000000008704b2a>] do_syscall_64+0x76/0x1a0 /arch/x86/entry/common.c:296
    [<000000009f4c57a4>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 30cc4587659e ("NFC: Move LLCP code to the NFC top level diirectory")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
---
 net/nfc/llcp_sock.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 8dfea26536c9d42a6bd9f7b64e3001737dbc4d89..ccdd790e163a81d0be5c69842fb3d25a57c743c4 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -107,9 +107,14 @@ static int llcp_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 	llcp_sock->service_name = kmemdup(llcp_addr.service_name,
 					  llcp_sock->service_name_len,
 					  GFP_KERNEL);
-
+	if (!llcp_sock->service_name) {
+		ret = -ENOMEM;
+		goto put_dev;
+	}
 	llcp_sock->ssap = nfc_llcp_get_sdp_ssap(local, llcp_sock);
 	if (llcp_sock->ssap == LLCP_SAP_MAX) {
+		kfree(llcp_sock->service_name);
+		llcp_sock->service_name = NULL;
 		ret = -EADDRINUSE;
 		goto put_dev;
 	}
-- 
2.23.0.581.g78d2f28ef7-goog