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    net_sched: fix error recovery at qdisc creation · 13550ffc
    Eric Dumazet authored
    commit 87b60cfa
    
     upstream.
    
    Dmitry reported uses after free in qdisc code [1]
    
    The problem here is that ops->init() can return an error.
    
    qdisc_create_dflt() then call ops->destroy(),
    while qdisc_create() does _not_ call it.
    
    Four qdisc chose to call their own ops->destroy(), assuming their caller
    would not.
    
    This patch makes sure qdisc_create() calls ops->destroy()
    and fixes the four qdisc to avoid double free.
    
    [1]
    BUG: KASAN: use-after-free in mq_destroy+0x242/0x290 net/sched/sch_mq.c:33 at addr ffff8801d415d440
    Read of size 8 by task syz-executor2/5030
    CPU: 0 PID: 5030 Comm: syz-executor2 Not tainted 4.3.5-smp-DEV #119
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
     0000000000000046 ffff8801b435b870 ffffffff81bbbed4 ffff8801db000400
     ffff8801d415d440 ffff8801d415dc40 ffff8801c4988510 ffff8801b435b898
     ffffffff816682b1 ffff8801b435b928 ffff8801d415d440 ffff8801c49880c0
    Call Trace:
     [<ffffffff81bbbed4>] __dump_stack lib/dump_stack.c:15 [inline]
     [<ffffffff81bbbed4>] dump_stack+0x6c/0x98 lib/dump_stack.c:51
     [<ffffffff816682b1>] kasan_object_err+0x21/0x70 mm/kasan/report.c:158
     [<ffffffff81668524>] print_address_description mm/kasan/report.c:196 [inline]
     [<ffffffff81668524>] kasan_report_error+0x1b4/0x4b0 mm/kasan/report.c:285
     [<ffffffff81668953>] kasan_report mm/kasan/report.c:305 [inline]
     [<ffffffff81668953>] __asan_report_load8_noabort+0x43/0x50 mm/kasan/report.c:326
     [<ffffffff82527b02>] mq_destroy+0x242/0x290 net/sched/sch_mq.c:33
     [<ffffffff82524bdd>] qdisc_destroy+0x12d/0x290 net/sched/sch_generic.c:953
     [<ffffffff82524e30>] qdisc_create_dflt+0xf0/0x120 net/sched/sch_generic.c:848
     [<ffffffff8252550d>] attach_default_qdiscs net/sched/sch_generic.c:1029 [inline]
     [<ffffffff8252550d>] dev_activate+0x6ad/0x880 net/sched/sch_generic.c:1064
     [<ffffffff824b1db1>] __dev_open+0x221/0x320 net/core/dev.c:1403
     [<ffffffff824b24ce>] __dev_change_flags+0x15e/0x3e0 net/core/dev.c:6858
     [<ffffffff824b27de>] dev_change_flags+0x8e/0x140 net/core/dev.c:6926
     [<ffffffff824f5bf6>] dev_ifsioc+0x446/0x890 net/core/dev_ioctl.c:260
     [<ffffffff824f61fa>] dev_ioctl+0x1ba/0xb80 net/core/dev_ioctl.c:546
     [<ffffffff82430509>] sock_do_ioctl+0x99/0xb0 net/socket.c:879
     [<ffffffff82430d30>] sock_ioctl+0x2a0/0x390 net/socket.c:958
     [<ffffffff816f3b68>] vfs_ioctl fs/ioctl.c:44 [inline]
     [<ffffffff816f3b68>] do_vfs_ioctl+0x8a8/0xe50 fs/ioctl.c:611
     [<ffffffff816f41a4>] SYSC_ioctl fs/ioctl.c:626 [inline]
     [<ffffffff816f41a4>] SyS_ioctl+0x94/0xc0 fs/ioctl.c:617
     [<ffffffff8123e357>] entry_SYSCALL_64_fastpath+0x12/0x17
    
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    13550ffc