• YueHaibing's avatar
    appletalk: Fix use-after-free in atalk_proc_exit · 0ba1fa56
    YueHaibing authored
    [ 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: 's avatarHulk Robot <hulkci@huawei.com>
    Signed-off-by: 's avatarYueHaibing <yuehaibing@huawei.com>
    Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: 's avatarSasha Levin <sashal@kernel.org>
    0ba1fa56
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