In the Linux kernel, the following vulnerability has been resolved: netrom: Fix memory leak in nr_sendmsg() syzbot reported a memory leak

In the Linux kernel, the following vulnerability has been resolved:

netrom: Fix memory leak in nr_sendmsg()

syzbot reported a memory leak [1].

When function sock_alloc_send_skb() return NULL in nr_output(), the
original skb is not freed, which was allocated in nr_sendmsg(). Fix this
by freeing it before return.

[1]
BUG: memory leak
unreferenced object 0xffff888129f35500 (size 240):
comm "syz.0.17", pid 6119, jiffies 4294944652
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 10 52 28 81 88 ff ff ..........R(....
backtrace (crc 1456a3e4):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4983 [inline]
slab_alloc_node mm/slub.c:5288 [inline]
kmem_cache_alloc_node_noprof+0x36f/0x5e0 mm/slub.c:5340
__alloc_skb+0x203/0x240 net/core/skbuff.c:660
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0x69/0x3f0 net/core/skbuff.c:6671
sock_alloc_send_pskb+0x379/0x3e0 net/core/sock.c:2965
sock_alloc_send_skb include/net/sock.h:1859 [inline]
nr_sendmsg+0x287/0x450 net/netrom/af_netrom.c:1105
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
sock_write_iter+0x293/0x2a0 net/socket.c:1195
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x45d/0x710 fs/read_write.c:686
ksys_write+0x143/0x170 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f