Re: KASAN: slab-out-of-bounds Read in ld_usb_read

[Andrey Konovalov]

On Mon, Aug 12, 2019 at 2:18 PM syzbot
<syzbot+ba00d6a2a24df57a94ca@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    e96407b4 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=162aac02600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
> dashboard link: https://syzkaller.appspot.com/bug?extid=ba00d6a2a24df57a94ca
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1123edc2600000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16079d2c600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+ba00d6a2a24df57a94ca@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ldusb 1-1:0.28: Read buffer overflow, -131386046930688 bytes dropped
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x124/0x150
> lib/usercopy.c:27
> Read of size 2147479552 at addr ffff8881cd580008 by task
> syz-executor268/1890
>
> CPU: 0 PID: 1890 Comm: syz-executor268 Not tainted 5.3.0-rc2+ #25
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0xca/0x13e lib/dump_stack.c:113
>   print_address_description+0x6a/0x32c mm/kasan/report.c:351
>   __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482
>   kasan_report+0xe/0x12 mm/kasan/common.c:612
>   check_memory_region_inline mm/kasan/generic.c:185 [inline]
>   check_memory_region+0x128/0x190 mm/kasan/generic.c:192
>   _copy_to_user+0x124/0x150 lib/usercopy.c:27
>   copy_to_user include/linux/uaccess.h:152 [inline]
>   ld_usb_read+0x31a/0x780 drivers/usb/misc/ldusb.c:495

#syz dup: KASAN: use-after-free Read in ld_usb_release

>   __vfs_read+0x76/0x100 fs/read_write.c:425
>   vfs_read+0x1ea/0x430 fs/read_write.c:461
>   ksys_read+0x1e8/0x250 fs/read_write.c:587
>   do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x441c49
> Code: e8 8c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 cb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffd920003d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441c49
> RDX: 00000000fffffd68 RSI: 0000000020000100 RDI: 0000000000000004
> RBP: 00000000000305b5 R08: 000000000000000f R09: 0000000000402a30
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004029a0
> R13: 0000000000402a30 R14: 0000000000000000 R15: 0000000000000000
>
> The buggy address belongs to the page:
> page:ffffea0007356000 refcount:1 mapcount:0 mapping:0000000000000000
> index:0x0 compound_mapcount: 0
> flags: 0x200000000010000(head)
> raw: 0200000000010000 dead000000000100 dead000000000122 0000000000000000
> raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff8881cd595500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   ffff8881cd595580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > ffff8881cd595600: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>                     ^
>   ffff8881cd595680: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>   ffff8881cd595700: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
> ==================================================================
>
>
> ---
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