CVE-2023-52577

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> dccp: fix dccp_v4_err()/dccp_v6_err() again<br /> <br /> dh-&gt;dccph_x is the 9th byte (offset 8) in "struct dccp_hdr",<br /> not in the "byte 7" as Jann claimed.<br /> <br /> We need to make sure the ICMP messages are big enough,<br /> using more standard ways (no more assumptions).<br /> <br /> syzbot reported:<br /> BUG: KMSAN: uninit-value in pskb_may_pull_reason include/linux/skbuff.h:2667 [inline]<br /> BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2681 [inline]<br /> BUG: KMSAN: uninit-value in dccp_v6_err+0x426/0x1aa0 net/dccp/ipv6.c:94<br /> pskb_may_pull_reason include/linux/skbuff.h:2667 [inline]<br /> pskb_may_pull include/linux/skbuff.h:2681 [inline]<br /> dccp_v6_err+0x426/0x1aa0 net/dccp/ipv6.c:94<br /> icmpv6_notify+0x4c7/0x880 net/ipv6/icmp.c:867<br /> icmpv6_rcv+0x19d5/0x30d0<br /> ip6_protocol_deliver_rcu+0xda6/0x2a60 net/ipv6/ip6_input.c:438<br /> ip6_input_finish net/ipv6/ip6_input.c:483 [inline]<br /> NF_HOOK include/linux/netfilter.h:304 [inline]<br /> ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492<br /> ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586<br /> dst_input include/net/dst.h:468 [inline]<br /> ip6_rcv_finish+0x5db/0x870 net/ipv6/ip6_input.c:79<br /> NF_HOOK include/linux/netfilter.h:304 [inline]<br /> ipv6_rcv+0xda/0x390 net/ipv6/ip6_input.c:310<br /> __netif_receive_skb_one_core net/core/dev.c:5523 [inline]<br /> __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5637<br /> netif_receive_skb_internal net/core/dev.c:5723 [inline]<br /> netif_receive_skb+0x58/0x660 net/core/dev.c:5782<br /> tun_rx_batched+0x83b/0x920<br /> tun_get_user+0x564c/0x6940 drivers/net/tun.c:2002<br /> tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048<br /> call_write_iter include/linux/fs.h:1985 [inline]<br /> new_sync_write fs/read_write.c:491 [inline]<br /> vfs_write+0x8ef/0x15c0 fs/read_write.c:584<br /> ksys_write+0x20f/0x4c0 fs/read_write.c:637<br /> __do_sys_write fs/read_write.c:649 [inline]<br /> __se_sys_write fs/read_write.c:646 [inline]<br /> __x64_sys_write+0x93/0xd0 fs/read_write.c:646<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> <br /> Uninit was created at:<br /> slab_post_alloc_hook+0x12f/0xb70 mm/slab.h:767<br /> slab_alloc_node mm/slub.c:3478 [inline]<br /> kmem_cache_alloc_node+0x577/0xa80 mm/slub.c:3523<br /> kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:559<br /> __alloc_skb+0x318/0x740 net/core/skbuff.c:650<br /> alloc_skb include/linux/skbuff.h:1286 [inline]<br /> alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6313<br /> sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2795<br /> tun_alloc_skb drivers/net/tun.c:1531 [inline]<br /> tun_get_user+0x23cf/0x6940 drivers/net/tun.c:1846<br /> tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048<br /> call_write_iter include/linux/fs.h:1985 [inline]<br /> new_sync_write fs/read_write.c:491 [inline]<br /> vfs_write+0x8ef/0x15c0 fs/read_write.c:584<br /> ksys_write+0x20f/0x4c0 fs/read_write.c:637<br /> __do_sys_write fs/read_write.c:649 [inline]<br /> __se_sys_write fs/read_write.c:646 [inline]<br /> __x64_sys_write+0x93/0xd0 fs/read_write.c:646<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> <br /> CPU: 0 PID: 4995 Comm: syz-executor153 Not tainted 6.6.0-rc1-syzkaller-00014-ga747acc0b752 #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023