CVE-2023-54004

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

udplite: Fix NULL pointer dereference in _skmemraiseallocated().

syzbot reported [0] a null-ptr-deref in skgetrmem0() while using IPPROTO_UDPLITE (0x88):

14:25:52 executing program 1: r0 = socket$inet6(0xa, 0x80002, 0x88)

We had a similar report [1] for probably skmemoryallocated_add() in __skmemraiseallocated(), and commit c915fe13cbaa ("udplite: fix NULL pointer dereference") fixed it by setting .memoryallocated for udpliteprot and udplitev6prot.

To fix the variant, we need to set either .sysctlwmemoffset or .sysctl_rmem.

Now UDP and UDPLITE share the same value for .memoryallocated, so we use the same .sysctlwmem_offset for UDP and UDPLITE.

KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 RIP: 0010:skgetrmem0 include/net/sock.h:2907 [inline] RIP: 0010:__skmemraise_allocated+0x806/0x17a0 net/core/sock.c:3006 Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000 RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8 RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000 R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0 Call Trace: <TASK> __skmemschedule+0x6c/0xe0 net/core/sock.c:3077 udprmemschedule net/ipv4/udp.c:1539 [inline] __udpenqueueschedule_skb+0x776/0xb30 net/ipv4/udp.c:1581 __udpv6queuercvskb net/ipv6/udp.c:666 [inline] udpv6queuercvoneskb+0xc39/0x16c0 net/ipv6/udp.c:775 udpv6queuercvskb+0x194/0xa10 net/ipv6/udp.c:793 __udp6libmcast_deliver net/ipv6/udp.c:906 [inline] __udp6librcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013 ip6protocoldeliverrcu+0x2e7/0x1250 net/ipv6/ip6input.c:437 ip6inputfinish+0x150/0x2f0 net/ipv6/ip6input.c:482 NFHOOK include/linux/netfilter.h:303 [inline] NFHOOK include/linux/netfilter.h:297 [inline] ip6input+0xa0/0xd0 net/ipv6/ip6input.c:491 ip6mcinput+0x40b/0xf50 net/ipv6/ip6input.c:585 dstinput include/net/dst.h:468 [inline] ip6rcvfinish net/ipv6/ip6input.c:79 [inline] NFHOOK include/linux/netfilter.h:303 [inline] NFHOOK include/linux/netfilter.h:297 [inline] ipv6rcv+0x250/0x380 net/ipv6/ip6input.c:309 __netifreceiveskbonecore+0x114/0x180 net/core/dev.c:5491 __netifreceiveskb+0x1f/0x1c0 net/core/dev.c:5605 netif_receiveskbinternal net/core/dev.c:5691 [inline] netifreceiveskb+0x133/0x7a0 net/core/dev.c:5750 tunrxbatched+0x4b3/0x7a0 drivers/net/tun.c:1553 tungetuser+0x2452/0x39c0 drivers/net/tun.c:1989 tunchrwriteiter+0xdf/0x200 drivers/net/tun.c:2035 callwriteiter include/linux/fs.h:1868 [inline] newsyncwrite fs/readwrite.c:491 [inline] vfswrite+0x945/0xd50 fs/readwrite.c:584 ksyswrite+0x12b/0x250 fs/readwrite.c:637 dosyscall32irqson arch/x86/entry/common.c:112 [inline] __dofastsyscall32+0x65/0xf0 arch/x86/entry/common.c:178 dofastsyscall32+0x33/0x70 arch/x86/entry/common.c:203 entrySYSENTERcompatafterhwframe+0x70/0x82 RIP: 0023:0xf7f21579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 ---truncated---