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    Subject[PATCH 5.0 84/93] appletalk: Fix use-after-free in atalk_proc_exit
    Date
    [ Upstream commit 6377f787aeb945cae7abbb6474798de129e1f3ac ]

    KASAN report this:

    BUG: KASAN: use-after-free in pde_subdir_find+0x12d/0x150 fs/proc/generic.c:71
    Read of size 8 at addr ffff8881f41fe5b0 by task syz-executor.0/2806

    CPU: 0 PID: 2806 Comm: syz-executor.0 Not tainted 5.0.0-rc7+ #45
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
    Call Trace:
    __dump_stack lib/dump_stack.c:77 [inline]
    dump_stack+0xfa/0x1ce lib/dump_stack.c:113
    print_address_description+0x65/0x270 mm/kasan/report.c:187
    kasan_report+0x149/0x18d mm/kasan/report.c:317
    pde_subdir_find+0x12d/0x150 fs/proc/generic.c:71
    remove_proc_entry+0xe8/0x420 fs/proc/generic.c:667
    atalk_proc_exit+0x18/0x820 [appletalk]
    atalk_exit+0xf/0x5a [appletalk]
    __do_sys_delete_module kernel/module.c:1018 [inline]
    __se_sys_delete_module kernel/module.c:961 [inline]
    __x64_sys_delete_module+0x3dc/0x5e0 kernel/module.c:961
    do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x462e99
    Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
    RSP: 002b:00007fb2de6b9c58 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
    RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99
    RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200001c0
    RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb2de6ba6bc
    R13: 00000000004bccaa R14: 00000000006f6bc8 R15: 00000000ffffffff

    Allocated by task 2806:
    set_track mm/kasan/common.c:85 [inline]
    __kasan_kmalloc.constprop.3+0xa0/0xd0 mm/kasan/common.c:496
    slab_post_alloc_hook mm/slab.h:444 [inline]
    slab_alloc_node mm/slub.c:2739 [inline]
    slab_alloc mm/slub.c:2747 [inline]
    kmem_cache_alloc+0xcf/0x250 mm/slub.c:2752
    kmem_cache_zalloc include/linux/slab.h:730 [inline]
    __proc_create+0x30f/0xa20 fs/proc/generic.c:408
    proc_mkdir_data+0x47/0x190 fs/proc/generic.c:469
    0xffffffffc10c01bb
    0xffffffffc10c0166
    do_one_initcall+0xfa/0x5ca init/main.c:887
    do_init_module+0x204/0x5f6 kernel/module.c:3460
    load_module+0x66b2/0x8570 kernel/module.c:3808
    __do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902
    do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    Freed by task 2806:
    set_track mm/kasan/common.c:85 [inline]
    __kasan_slab_free+0x130/0x180 mm/kasan/common.c:458
    slab_free_hook mm/slub.c:1409 [inline]
    slab_free_freelist_hook mm/slub.c:1436 [inline]
    slab_free mm/slub.c:2986 [inline]
    kmem_cache_free+0xa6/0x2a0 mm/slub.c:3002
    pde_put+0x6e/0x80 fs/proc/generic.c:647
    remove_proc_entry+0x1d3/0x420 fs/proc/generic.c:684
    0xffffffffc10c031c
    0xffffffffc10c0166
    do_one_initcall+0xfa/0x5ca init/main.c:887
    do_init_module+0x204/0x5f6 kernel/module.c:3460
    load_module+0x66b2/0x8570 kernel/module.c:3808
    __do_sys_finit_module+0x238/0x2a0 kernel/module.c:3902
    do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    The buggy address belongs to the object at ffff8881f41fe500
    which belongs to the cache proc_dir_entry of size 256
    The buggy address is located 176 bytes inside of
    256-byte region [ffff8881f41fe500, ffff8881f41fe600)
    The buggy address belongs to the page:
    page:ffffea0007d07f80 count:1 mapcount:0 mapping:ffff8881f6e69a00 index:0x0
    flags: 0x2fffc0000000200(slab)
    raw: 02fffc0000000200 dead000000000100 dead000000000200 ffff8881f6e69a00
    raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
    page dumped because: kasan: bad access detected

    Memory state around the buggy address:
    ffff8881f41fe480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
    ffff8881f41fe500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    >ffff8881f41fe580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ^
    ffff8881f41fe600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
    ffff8881f41fe680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

    It should check the return value of atalk_proc_init fails,
    otherwise atalk_exit will trgger use-after-free in pde_subdir_find
    while unload the module.This patch fix error cleanup path of atalk_init

    Reported-by: Hulk Robot <hulkci@huawei.com>
    Signed-off-by: YueHaibing <yuehaibing@huawei.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    include/linux/atalk.h | 2 +-
    net/appletalk/atalk_proc.c | 2 +-
    net/appletalk/ddp.c | 37 ++++++++++++++++++++++++++------
    net/appletalk/sysctl_net_atalk.c | 5 ++++-
    4 files changed, 37 insertions(+), 9 deletions(-)

    diff --git a/include/linux/atalk.h b/include/linux/atalk.h
    index 840cf92307ba..d5cfc0b15b76 100644
    --- a/include/linux/atalk.h
    +++ b/include/linux/atalk.h
    @@ -158,7 +158,7 @@ extern int sysctl_aarp_retransmit_limit;
    extern int sysctl_aarp_resolve_time;

    #ifdef CONFIG_SYSCTL
    -extern void atalk_register_sysctl(void);
    +extern int atalk_register_sysctl(void);
    extern void atalk_unregister_sysctl(void);
    #else
    static inline int atalk_register_sysctl(void)
    diff --git a/net/appletalk/atalk_proc.c b/net/appletalk/atalk_proc.c
    index 8006295f8bd7..dda73991bb54 100644
    --- a/net/appletalk/atalk_proc.c
    +++ b/net/appletalk/atalk_proc.c
    @@ -255,7 +255,7 @@ int __init atalk_proc_init(void)
    goto out;
    }

    -void __exit atalk_proc_exit(void)
    +void atalk_proc_exit(void)
    {
    remove_proc_entry("interface", atalk_proc_dir);
    remove_proc_entry("route", atalk_proc_dir);
    diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
    index 9b6bc5abe946..795fbc6c06aa 100644
    --- a/net/appletalk/ddp.c
    +++ b/net/appletalk/ddp.c
    @@ -1910,12 +1910,16 @@ static const char atalk_err_snap[] __initconst =
    /* Called by proto.c on kernel start up */
    static int __init atalk_init(void)
    {
    - int rc = proto_register(&ddp_proto, 0);
    + int rc;

    - if (rc != 0)
    + rc = proto_register(&ddp_proto, 0);
    + if (rc)
    goto out;

    - (void)sock_register(&atalk_family_ops);
    + rc = sock_register(&atalk_family_ops);
    + if (rc)
    + goto out_proto;
    +
    ddp_dl = register_snap_client(ddp_snap_id, atalk_rcv);
    if (!ddp_dl)
    printk(atalk_err_snap);
    @@ -1923,12 +1927,33 @@ static int __init atalk_init(void)
    dev_add_pack(&ltalk_packet_type);
    dev_add_pack(&ppptalk_packet_type);

    - register_netdevice_notifier(&ddp_notifier);
    + rc = register_netdevice_notifier(&ddp_notifier);
    + if (rc)
    + goto out_sock;
    +
    aarp_proto_init();
    - atalk_proc_init();
    - atalk_register_sysctl();
    + rc = atalk_proc_init();
    + if (rc)
    + goto out_aarp;
    +
    + rc = atalk_register_sysctl();
    + if (rc)
    + goto out_proc;
    out:
    return rc;
    +out_proc:
    + atalk_proc_exit();
    +out_aarp:
    + aarp_cleanup_module();
    + unregister_netdevice_notifier(&ddp_notifier);
    +out_sock:
    + dev_remove_pack(&ppptalk_packet_type);
    + dev_remove_pack(&ltalk_packet_type);
    + unregister_snap_client(ddp_dl);
    + sock_unregister(PF_APPLETALK);
    +out_proto:
    + proto_unregister(&ddp_proto);
    + goto out;
    }
    module_init(atalk_init);

    diff --git a/net/appletalk/sysctl_net_atalk.c b/net/appletalk/sysctl_net_atalk.c
    index c744a853fa5f..d945b7c0176d 100644
    --- a/net/appletalk/sysctl_net_atalk.c
    +++ b/net/appletalk/sysctl_net_atalk.c
    @@ -45,9 +45,12 @@ static struct ctl_table atalk_table[] = {

    static struct ctl_table_header *atalk_table_header;

    -void atalk_register_sysctl(void)
    +int __init atalk_register_sysctl(void)
    {
    atalk_table_header = register_net_sysctl(&init_net, "net/appletalk", atalk_table);
    + if (!atalk_table_header)
    + return -ENOMEM;
    + return 0;
    }

    void atalk_unregister_sysctl(void)
    --
    2.19.1


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