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[ Upstream commit d9f92772e8ec388d070752ee8f187ef8fa18621f ] syzbot found a way to trigger an infinitie loop by overflowing @offset variable that has been forced to use u16 for some very obscure reason in the past. We probably want to look at NEXTHDR_FRAGMENT handling which looks wrong, in a separate patch. In net-next, we shall try to use skb_header_pointer() instead of pskb_may_pull(). watchdog: BUG: soft lockup - CPU#1 stuck for 134s! [syz-executor738:4553] Modules linked in: irq event stamp: 13885653 hardirqs last enabled at (13885652): [<ffffffff878009d5>] restore_regs_and_return_to_kernel+0x0/0x2b hardirqs last disabled at (13885653): [<ffffffff87800905>] interrupt_entry+0xb5/0xf0 arch/x86/entry/entry_64.S:625 softirqs last enabled at (13614028): [<ffffffff84df0809>] tun_napi_alloc_frags drivers/net/tun.c:1478 [inline] softirqs last enabled at (13614028): [<ffffffff84df0809>] tun_get_user+0x1dd9/0x4290 drivers/net/tun.c:1825 softirqs last disabled at (13614032): [<ffffffff84df1b6f>] tun_get_user+0x313f/0x4290 drivers/net/tun.c:1942 CPU: 1 PID: 4553 Comm: syz-executor738 Not tainted 4.17.0-rc3+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_kcov_mode kernel/kcov.c:67 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x20/0x50 kernel/kcov.c:101 RSP: 0018:ffff8801d8cfe250 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffff8801d88a8080 RBX: ffff8801d7389e40 RCX: 0000000000000006 RDX: 0000000000000000 RSI: ffffffff868da4ad RDI: ffff8801c8a53277 RBP: ffff8801d8cfe250 R08: ffff8801d88a8080 R09: ffff8801d8cfe3e8 R10: ffffed003b19fc87 R11: ffff8801d8cfe43f R12: ffff8801c8a5327f R13: 0000000000000000 R14: ffff8801c8a4e5fe R15: ffff8801d8cfe3e8 FS: 0000000000d88940(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001acab3000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: _decode_session6+0xc1d/0x14f0 net/ipv6/xfrm6_policy.c:150 __xfrm_decode_session+0x71/0x140 net/xfrm/xfrm_policy.c:2368 xfrm_decode_session_reverse include/net/xfrm.h:1213 [inline] icmpv6_route_lookup+0x395/0x6e0 net/ipv6/icmp.c:372 icmp6_send+0x1982/0x2da0 net/ipv6/icmp.c:551 icmpv6_send+0x17a/0x300 net/ipv6/ip6_icmp.c:43 ip6_input_finish+0x14e1/0x1a30 net/ipv6/ip6_input.c:305 NF_HOOK include/linux/netfilter.h:288 [inline] ip6_input+0xe1/0x5e0 net/ipv6/ip6_input.c:327 dst_input include/net/dst.h:450 [inline] ip6_rcv_finish+0x29c/0xa10 net/ipv6/ip6_input.c:71 NF_HOOK include/linux/netfilter.h:288 [inline] ipv6_rcv+0xeb8/0x2040 net/ipv6/ip6_input.c:208 __netif_receive_skb_core+0x2468/0x3650 net/core/dev.c:4646 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:4711 netif_receive_skb_internal+0x126/0x7b0 net/core/dev.c:4785 napi_frags_finish net/core/dev.c:5226 [inline] napi_gro_frags+0x631/0xc40 net/core/dev.c:5299 tun_get_user+0x3168/0x4290 drivers/net/tun.c:1951 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1996 call_write_iter include/linux/fs.h:1784 [inline] do_iter_readv_writev+0x859/0xa50 fs/read_write.c:680 do_iter_write+0x185/0x5f0 fs/read_write.c:959 vfs_writev+0x1c7/0x330 fs/read_write.c:1004 do_writev+0x112/0x2f0 fs/read_write.c:1039 __do_sys_writev fs/read_write.c:1112 [inline] __se_sys_writev fs/read_write.c:1109 [inline] __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com> Reported-by: syzbot+0053c8...@syzkaller.appspotmail.com Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.