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    Subject[PATCH 5.10 173/199] net_sched: avoid shift-out-of-bounds in tcindex_set_parms()
    Date
    From: Eric Dumazet <edumazet@google.com>

    commit bcd0cf19ef8258ac31b9a20248b05c15a1f4b4b0 upstream.

    tc_index being 16bit wide, we need to check that TCA_TCINDEX_SHIFT
    attribute is not silly.

    UBSAN: shift-out-of-bounds in net/sched/cls_tcindex.c:260:29
    shift exponent 255 is too large for 32-bit type 'int'
    CPU: 0 PID: 8516 Comm: syz-executor228 Not tainted 5.10.0-syzkaller #0
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
    __dump_stack lib/dump_stack.c:79 [inline]
    dump_stack+0x107/0x163 lib/dump_stack.c:120
    ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
    __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
    valid_perfect_hash net/sched/cls_tcindex.c:260 [inline]
    tcindex_set_parms.cold+0x1b/0x215 net/sched/cls_tcindex.c:425
    tcindex_change+0x232/0x340 net/sched/cls_tcindex.c:546
    tc_new_tfilter+0x13fb/0x21b0 net/sched/cls_api.c:2127
    rtnetlink_rcv_msg+0x8b6/0xb80 net/core/rtnetlink.c:5555
    netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
    netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
    netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
    netlink_sendmsg+0x907/0xe40 net/netlink/af_netlink.c:1919
    sock_sendmsg_nosec net/socket.c:652 [inline]
    sock_sendmsg+0xcf/0x120 net/socket.c:672
    ____sys_sendmsg+0x6e8/0x810 net/socket.c:2336
    ___sys_sendmsg+0xf3/0x170 net/socket.c:2390
    __sys_sendmsg+0xe5/0x1b0 net/socket.c:2423
    do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

    Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Reported-by: syzbot <syzkaller@googlegroups.com>
    Link: https://lore.kernel.org/r/20210114185229.1742255-1-eric.dumazet@gmail.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/sched/cls_tcindex.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    --- a/net/sched/cls_tcindex.c
    +++ b/net/sched/cls_tcindex.c
    @@ -366,9 +366,13 @@ tcindex_set_parms(struct net *net, struc
    if (tb[TCA_TCINDEX_MASK])
    cp->mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);

    - if (tb[TCA_TCINDEX_SHIFT])
    + if (tb[TCA_TCINDEX_SHIFT]) {
    cp->shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
    -
    + if (cp->shift > 16) {
    + err = -EINVAL;
    + goto errout;
    + }
    + }
    if (!cp->hash) {
    /* Hash not specified, use perfect hash if the upper limit
    * of the hashing index is below the threshold.

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