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    Subject[PATCH 4.16 51/81] net: validate attribute sizes in neigh_dump_table()
    Date
    4.16-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Dumazet <edumazet@google.com>


    [ Upstream commit 7dd07c143a4b54d050e748bee4b4b9e94a7b1744 ]

    Since neigh_dump_table() calls nlmsg_parse() without giving policy
    constraints, attributes can have arbirary size that we must validate

    Reported by syzbot/KMSAN :

    BUG: KMSAN: uninit-value in neigh_master_filtered net/core/neighbour.c:2292 [inline]
    BUG: KMSAN: uninit-value in neigh_dump_table net/core/neighbour.c:2348 [inline]
    BUG: KMSAN: uninit-value in neigh_dump_info+0x1af0/0x2250 net/core/neighbour.c:2438
    CPU: 1 PID: 3575 Comm: syzkaller268891 Not tainted 4.16.0+ #83
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
    __dump_stack lib/dump_stack.c:17 [inline]
    dump_stack+0x185/0x1d0 lib/dump_stack.c:53
    kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
    __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
    neigh_master_filtered net/core/neighbour.c:2292 [inline]
    neigh_dump_table net/core/neighbour.c:2348 [inline]
    neigh_dump_info+0x1af0/0x2250 net/core/neighbour.c:2438
    netlink_dump+0x9ad/0x1540 net/netlink/af_netlink.c:2225
    __netlink_dump_start+0x1167/0x12a0 net/netlink/af_netlink.c:2322
    netlink_dump_start include/linux/netlink.h:214 [inline]
    rtnetlink_rcv_msg+0x1435/0x1560 net/core/rtnetlink.c:4598
    netlink_rcv_skb+0x355/0x5f0 net/netlink/af_netlink.c:2447
    rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4653
    netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
    netlink_unicast+0x1672/0x1750 net/netlink/af_netlink.c:1337
    netlink_sendmsg+0x1048/0x1310 net/netlink/af_netlink.c:1900
    sock_sendmsg_nosec net/socket.c:630 [inline]
    sock_sendmsg net/socket.c:640 [inline]
    ___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
    __sys_sendmsg net/socket.c:2080 [inline]
    SYSC_sendmsg+0x2a3/0x3d0 net/socket.c:2091
    SyS_sendmsg+0x54/0x80 net/socket.c:2087
    do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
    entry_SYSCALL_64_after_hwframe+0x3d/0xa2
    RIP: 0033:0x43fed9
    RSP: 002b:00007ffddbee2798 EFLAGS: 00000213 ORIG_RAX: 000000000000002e
    RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fed9
    RDX: 0000000000000000 RSI: 0000000020005000 RDI: 0000000000000003
    RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
    R10: 00000000004002c8 R11: 0000000000000213 R12: 0000000000401800
    R13: 0000000000401890 R14: 0000000000000000 R15: 0000000000000000

    Uninit was created at:
    kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
    kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
    kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
    kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321
    slab_post_alloc_hook mm/slab.h:445 [inline]
    slab_alloc_node mm/slub.c:2737 [inline]
    __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369
    __kmalloc_reserve net/core/skbuff.c:138 [inline]
    __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206
    alloc_skb include/linux/skbuff.h:984 [inline]
    netlink_alloc_large_skb net/netlink/af_netlink.c:1183 [inline]
    netlink_sendmsg+0x9a6/0x1310 net/netlink/af_netlink.c:1875
    sock_sendmsg_nosec net/socket.c:630 [inline]
    sock_sendmsg net/socket.c:640 [inline]
    ___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
    __sys_sendmsg net/socket.c:2080 [inline]
    SYSC_sendmsg+0x2a3/0x3d0 net/socket.c:2091
    SyS_sendmsg+0x54/0x80 net/socket.c:2087
    do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
    entry_SYSCALL_64_after_hwframe+0x3d/0xa2

    Fixes: 21fdd092acc7 ("net: Add support for filtering neigh dump by master device")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Cc: David Ahern <dsa@cumulusnetworks.com>
    Reported-by: syzbot <syzkaller@googlegroups.com>
    Acked-by: David Ahern <dsa@cumulusnetworks.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/core/neighbour.c | 12 ++++++++----
    1 file changed, 8 insertions(+), 4 deletions(-)

    --- a/net/core/neighbour.c
    +++ b/net/core/neighbour.c
    @@ -2331,12 +2331,16 @@ static int neigh_dump_table(struct neigh

    err = nlmsg_parse(nlh, sizeof(struct ndmsg), tb, NDA_MAX, NULL, NULL);
    if (!err) {
    - if (tb[NDA_IFINDEX])
    + if (tb[NDA_IFINDEX]) {
    + if (nla_len(tb[NDA_IFINDEX]) != sizeof(u32))
    + return -EINVAL;
    filter_idx = nla_get_u32(tb[NDA_IFINDEX]);
    -
    - if (tb[NDA_MASTER])
    + }
    + if (tb[NDA_MASTER]) {
    + if (nla_len(tb[NDA_MASTER]) != sizeof(u32))
    + return -EINVAL;
    filter_master_idx = nla_get_u32(tb[NDA_MASTER]);
    -
    + }
    if (filter_idx || filter_master_idx)
    flags |= NLM_F_DUMP_FILTERED;
    }

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