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In fib6_add(), it is possible that fib6_add_1() picks an intermediate node and sets the node's fn->leaf to NULL in order to add this new route. However, if fib6_add_rt2node() fails to add the new route for some reason, fn->leaf will be left as NULL and could potentially cause crash when fn->leaf is accessed in fib6_locate(). This patch makes sure fib6_repair_tree() is called to properly repair fn->leaf in the above failure case. Here is the syzkaller reported general protection fault in fib6_locate: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Modules linked in: CPU: 0 PID: 40937 Comm: syz-executor3 Not tainted Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d7d64100 ti: ffff8801d01a0000 task.ti: ffff8801d01a0000 RIP: 0010:[<ffffffff82a3e0e1>] [<ffffffff82a3e0e1>] __ipv6_prefix_equal64_half include/net/ipv6.h:475 [inline] RIP: 0010:[<ffffffff82a3e0e1>] [<ffffffff82a3e0e1>] ipv6_prefix_equal include/net/ipv6.h:492 [inline] RIP: 0010:[<ffffffff82a3e0e1>] [<ffffffff82a3e0e1>] fib6_locate_1 net/ipv6/ip6_fib.c:1210 [inline] RIP: 0010:[<ffffffff82a3e0e1>] [<ffffffff82a3e0e1>] fib6_locate+0x281/0x3c0 net/ipv6/ip6_fib.c:1233 RSP: 0018:ffff8801d01a36a8 EFLAGS: 00010202 RAX: 0000000000000020 RBX: ffff8801bc790e00 RCX: ffffc90002983000 RDX: 0000000000001219 RSI: ffff8801d01a37a0 RDI: 0000000000000100 RBP: ffff8801d01a36f0 R08: 00000000000000ff R09: 0000000000000000 R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000000001 R13: dffffc0000000000 R14: ffff8801d01a37a0 R15: 0000000000000000 FS: 00007f6afd68c700(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004c6340 CR3: 00000000ba41f000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8801d01a37a8 ffff8801d01a3780 ffffed003a0346f5 0000000c82a23ea0 ffff8800b7bd7700 ffff8801d01a3780 ffff8800b6a1c940 ffffffff82a23ea0 ffff8801d01a3920 ffff8801d01a3748 ffffffff82a223d6 ffff8801d7d64988 Call Trace: [<ffffffff82a223d6>] ip6_route_del+0x106/0x570 net/ipv6/route.c:2109 [<ffffffff82a23f9d>] inet6_rtm_delroute+0xfd/0x100 net/ipv6/route.c:3075 [<ffffffff82621359>] rtnetlink_rcv_msg+0x549/0x7a0 net/core/rtnetlink.c:3450 [<ffffffff8274c1d1>] netlink_rcv_skb+0x141/0x370 net/netlink/af_netlink.c:2281 [<ffffffff82613ddf>] rtnetlink_rcv+0x2f/0x40 net/core/rtnetlink.c:3456 [<ffffffff8274ad38>] netlink_unicast_kernel net/netlink/af_netlink.c:1206 [inline] [<ffffffff8274ad38>] netlink_unicast+0x518/0x750 net/netlink/af_netlink.c:1232 [<ffffffff8274b83e>] netlink_sendmsg+0x8ce/0xc30 net/netlink/af_netlink.c:1778 [<ffffffff82564aff>] sock_sendmsg_nosec net/socket.c:609 [inline] [<ffffffff82564aff>] sock_sendmsg+0xcf/0x110 net/socket.c:619 [<ffffffff82564d62>] sock_write_iter+0x222/0x3a0 net/socket.c:834 [<ffffffff8178523d>] new_sync_write+0x1dd/0x2b0 fs/read_write.c:478 [<ffffffff817853f4>] __vfs_write+0xe4/0x110 fs/read_write.c:491 [<ffffffff81786c38>] vfs_write+0x178/0x4b0 fs/read_write.c:538 [<ffffffff817892a9>] SYSC_write fs/read_write.c:585 [inline] [<ffffffff817892a9>] SyS_write+0xd9/0x1b0 fs/read_write.c:577 [<ffffffff82c71e32>] entry_SYSCALL_64_fastpath+0x12/0x17 Note: there is no "Fixes" tag as this seems to be a bug introduced very early. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.