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b3979e3d2f
syzkaller created an IPv6 route from a malformed packet, which has a prefix len > 128, triggering the splat below. [0] This is a similar issue fixed by commit586ceac9ac("ipv6: Restore fib6_config validation for SIOCADDRT."). The cited commit removed fib6_config validation from some callers of ip6_add_route(). Let's move the validation back to ip6_route_add() and ip6_route_multipath_add(). [0]: UBSAN: array-index-out-of-bounds in ./include/net/ipv6.h:616:34 index 20 is out of range for type '__u8 [16]' CPU: 1 UID: 0 PID: 7444 Comm: syz.0.708 Not tainted 6.16.0-rc1-syzkaller-g19272b37aa4f #0 PREEMPT Hardware name: riscv-virtio,qemu (DT) Call Trace: [<ffffffff80078a80>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:132 [<ffffffff8000327a>] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:138 [<ffffffff80061012>] __dump_stack lib/dump_stack.c:94 [inline] [<ffffffff80061012>] dump_stack_lvl+0x12e/0x1a6 lib/dump_stack.c:120 [<ffffffff800610a6>] dump_stack+0x1c/0x24 lib/dump_stack.c:129 [<ffffffff8001c0ea>] ubsan_epilogue+0x14/0x46 lib/ubsan.c:233 [<ffffffff819ba290>] __ubsan_handle_out_of_bounds+0xf6/0xf8 lib/ubsan.c:455 [<ffffffff85b363a4>] ipv6_addr_prefix include/net/ipv6.h:616 [inline] [<ffffffff85b363a4>] ip6_route_info_create+0x8f8/0x96e net/ipv6/route.c:3793 [<ffffffff85b635da>] ip6_route_add+0x2a/0x1aa net/ipv6/route.c:3889 [<ffffffff85b02e08>] addrconf_prefix_route+0x2c4/0x4e8 net/ipv6/addrconf.c:2487 [<ffffffff85b23bb2>] addrconf_prefix_rcv+0x1720/0x1e62 net/ipv6/addrconf.c:2878 [<ffffffff85b92664>] ndisc_router_discovery+0x1a06/0x3504 net/ipv6/ndisc.c:1570 [<ffffffff85b99038>] ndisc_rcv+0x500/0x600 net/ipv6/ndisc.c:1874 [<ffffffff85bc2c18>] icmpv6_rcv+0x145e/0x1e0a net/ipv6/icmp.c:988 [<ffffffff85af6798>] ip6_protocol_deliver_rcu+0x18a/0x1976 net/ipv6/ip6_input.c:436 [<ffffffff85af8078>] ip6_input_finish+0xf4/0x174 net/ipv6/ip6_input.c:480 [<ffffffff85af8262>] NF_HOOK include/linux/netfilter.h:317 [inline] [<ffffffff85af8262>] NF_HOOK include/linux/netfilter.h:311 [inline] [<ffffffff85af8262>] ip6_input+0x16a/0x70c net/ipv6/ip6_input.c:491 [<ffffffff85af8dcc>] ip6_mc_input+0x5c8/0x1268 net/ipv6/ip6_input.c:588 [<ffffffff85af6112>] dst_input include/net/dst.h:469 [inline] [<ffffffff85af6112>] ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline] [<ffffffff85af6112>] NF_HOOK include/linux/netfilter.h:317 [inline] [<ffffffff85af6112>] NF_HOOK include/linux/netfilter.h:311 [inline] [<ffffffff85af6112>] ipv6_rcv+0x5ae/0x6e0 net/ipv6/ip6_input.c:309 [<ffffffff85087e84>] __netif_receive_skb_one_core+0x106/0x16e net/core/dev.c:5977 [<ffffffff85088104>] __netif_receive_skb+0x2c/0x144 net/core/dev.c:6090 [<ffffffff850883c6>] netif_receive_skb_internal net/core/dev.c:6176 [inline] [<ffffffff850883c6>] netif_receive_skb+0x1aa/0xbf2 net/core/dev.c:6235 [<ffffffff8328656e>] tun_rx_batched.isra.0+0x430/0x686 drivers/net/tun.c:1485 [<ffffffff8329ed3a>] tun_get_user+0x2952/0x3d6c drivers/net/tun.c:1938 [<ffffffff832a21e0>] tun_chr_write_iter+0xc4/0x21c drivers/net/tun.c:1984 [<ffffffff80b9b9ae>] new_sync_write fs/read_write.c:593 [inline] [<ffffffff80b9b9ae>] vfs_write+0x56c/0xa9a fs/read_write.c:686 [<ffffffff80b9c2be>] ksys_write+0x126/0x228 fs/read_write.c:738 [<ffffffff80b9c42e>] __do_sys_write fs/read_write.c:749 [inline] [<ffffffff80b9c42e>] __se_sys_write fs/read_write.c:746 [inline] [<ffffffff80b9c42e>] __riscv_sys_write+0x6e/0x94 fs/read_write.c:746 [<ffffffff80076912>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 [<ffffffff8637e31e>] do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:341 [<ffffffff863a69e2>] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 Fixes:fa76c1674f("ipv6: Move some validation from ip6_route_info_create() to rtm_to_fib6_config().") Reported-by: syzbot+4c2358694722d304c44e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6849b8c3.a00a0220.1eb5f5.00f0.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250611193551.2999991-1-kuni1840@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
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.