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

hsr: Fix uninit-value access in hsrgetnode()

KMSAN reported the following uninit-value access issue [1]:

===================================================== BUG: KMSAN: uninit-value in hsrgetnode+0xa2e/0xa40 net/hsr/hsrframereg.c:246 hsrgetnode+0xa2e/0xa40 net/hsr/hsrframereg.c:246 fillframeinfo net/hsr/hsrforward.c:577 [inline] hsrforwardskb+0xe12/0x30e0 net/hsr/hsrforward.c:615 hsrdevxmit+0x1a1/0x270 net/hsr/hsrdevice.c:223 _netdevstartxmit include/linux/netdevice.h:4940 [inline] netdevstartxmit include/linux/netdevice.h:4954 [inline] xmitone net/core/dev.c:3548 [inline] devhardstartxmit+0x247/0xa10 net/core/dev.c:3564 _devqueuexmit+0x33b8/0x5130 net/core/dev.c:4349 devqueuexmit include/linux/netdevice.h:3134 [inline] packetxmit+0x9c/0x6b0 net/packet/afpacket.c:276 packetsnd net/packet/afpacket.c:3087 [inline] packetsendmsg+0x8b1d/0x9f30 net/packet/afpacket.c:3119 socksendmsgnosec net/socket.c:730 [inline] _socksendmsg net/socket.c:745 [inline] _syssendto+0x735/0xa10 net/socket.c:2191 _dosyssendto net/socket.c:2203 [inline] _sesyssendto net/socket.c:2199 [inline] _x64syssendto+0x125/0x1c0 net/socket.c:2199 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0x6d/0x140 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x63/0x6b

Uninit was created at: slabpostallochook+0x129/0xa70 mm/slab.h:768 slaballocnode mm/slub.c:3478 [inline] kmemcacheallocnode+0x5e9/0xb10 mm/slub.c:3523 kmallocreserve+0x13d/0x4a0 net/core/skbuff.c:560 _allocskb+0x318/0x740 net/core/skbuff.c:651 allocskb include/linux/skbuff.h:1286 [inline] allocskbwithfrags+0xc8/0xbd0 net/core/skbuff.c:6334 sockallocsendpskb+0xa80/0xbf0 net/core/sock.c:2787 packetallocskb net/packet/afpacket.c:2936 [inline] packetsnd net/packet/afpacket.c:3030 [inline] packetsendmsg+0x70e8/0x9f30 net/packet/afpacket.c:3119 socksendmsgnosec net/socket.c:730 [inline] _socksendmsg net/socket.c:745 [inline] _syssendto+0x735/0xa10 net/socket.c:2191 _dosyssendto net/socket.c:2203 [inline] _sesyssendto net/socket.c:2199 [inline] _x64syssendto+0x125/0x1c0 net/socket.c:2199 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0x6d/0x140 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x63/0x6b

CPU: 1 PID: 5033 Comm: syz-executor334 Not tainted 6.7.0-syzkaller-00562-g9f8413c4a66f #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023

If the packet type ID field in the Ethernet header is either ETHPPRP or ETHPHSR, but it is not followed by an HSR tag, hsrgetskbsequencenr() reads an invalid value as a sequence number. This causes the above issue.

This patch fixes the issue by returning NULL if the Ethernet header is not followed by an HSR tag.