CVE-2022-50817

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

net: hsr: avoid possible NULL deref in skb_clone()

syzbot got a crash [1] in skbclone(), caused by a bug in hsrgetuntaggedframe().

When/if createstrippedskbhsr() returns NULL, we must not attempt to call skbclone().

While we are at it, replace a WARNONCE() by netdevwarn_once().

[1] general protection fault, probably for non-canonical address 0xdffffc000000000f: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f] CPU: 1 PID: 754 Comm: syz-executor.0 Not tainted 6.0.0-syzkaller-02734-g0326074ff465 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022 RIP: 0010:skb_clone+0x108/0x3c0 net/core/skbuff.c:1641 Code: 93 02 00 00 49 83 7c 24 28 00 0f 85 e9 00 00 00 e8 5d 4a 29 fa 4c 8d 75 7e 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <0f> b6 04 02 4c 89 f2 83 e2 07 38 d0 7f 08 84 c0 0f 85 9e 01 00 00 RSP: 0018:ffffc90003ccf4e0 EFLAGS: 00010207

RAX: dffffc0000000000 RBX: ffffc90003ccf5f8 RCX: ffffc9000c24b000 RDX: 000000000000000f RSI: ffffffff8751cb13 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00000000000000f0 R09: 0000000000000140 R10: fffffbfff181d972 R11: 0000000000000000 R12: ffff888161fc3640 R13: 0000000000000a20 R14: 000000000000007e R15: ffffffff8dc5f620 FS: 00007feb621e4700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007feb621e3ff8 CR3: 00000001643a9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> hsrgetuntaggedframe+0x4e/0x610 net/hsr/hsrforward.c:164 hsrforwarddo net/hsr/hsrforward.c:461 [inline] hsrforwardskb+0xcca/0x1d50 net/hsr/hsrforward.c:623 hsrhandleframe+0x588/0x7c0 net/hsr/hsr_slave.c:69 __netifreceiveskb_core+0x9fe/0x38f0 net/core/dev.c:5379 __netifreceiveskbonecore+0xae/0x180 net/core/dev.c:5483 _netifreceiveskb+0x1f/0x1c0 net/core/dev.c:5599 netifreceiveskbinternal net/core/dev.c:5685 [inline] netifreceiveskb+0x12f/0x8d0 net/core/dev.c:5744 tunrxbatched+0x4ab/0x7a0 drivers/net/tun.c:1544 tungetuser+0x2686/0x3a00 drivers/net/tun.c:1995 tunchrwriteiter+0xdb/0x200 drivers/net/tun.c:2025 callwriteiter include/linux/fs.h:2187 [inline] newsyncwrite fs/readwrite.c:491 [inline] vfswrite+0x9e9/0xdd0 fs/readwrite.c:584 ksyswrite+0x127/0x250 fs/readwrite.c:637 dosyscallx64 arch/x86/entry/common.c:50 [inline] dosyscall64+0x35/0xb0 arch/x86/entry/common.c:80 entrySYSCALL64afterhwframe+0x63/0xcd