Re: KASAN: stack-out-of-bounds Read in rdma_bind_addr (2)

[Leon Romanovsky]

#syz dup: kernel BUG at lib/string.c:LINE! (3)

On Thu, Mar 29, 2018 at 03:01:02PM -0700, syzbot wrote:
> Hello,
>
> syzbot hit the following crash on upstream commit
> 0b412605ef5f5c64b31f19e2910b1d5eba9929c3 (Thu Mar 29 01:07:23 2018 +0000)
> Merge tag 'drm-fixes-for-v4.16-rc8' of
> git://people.freedesktop.org/~airlied/linux
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=4b6afe4bdd99cb99e664
>
> So far this crash happened 4 times on upstream.
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6021023174492160
> syzkaller reproducer:
> https://syzkaller.appspot.com/x/repro.syz?id=6269942299099136
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=6347752745205760
> Kernel config:
> https://syzkaller.appspot.com/x/.config?id=-8440362230543204781
> compiler: gcc (GCC) 7.1.1 20170620
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+4b6afe4bdd99cb99e664@xxxxxxxxxxxxxxxxxxxxxxxxx
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.
>
> ==================================================================
> BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:345
> [inline]
> BUG: KASAN: stack-out-of-bounds in rdma_bind_addr+0x13b/0x1d60
> drivers/infiniband/core/cma.c:3361
> Read of size 48 at addr ffff8801af717a50 by task syzkaller366236/4421
>
> CPU: 0 PID: 4421 Comm: syzkaller366236 Not tainted 4.16.0-rc7+ #5
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x24d lib/dump_stack.c:53
>  print_address_description+0x73/0x250 mm/kasan/report.c:256
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report+0x23c/0x360 mm/kasan/report.c:412
>  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
>  check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
>  memcpy+0x23/0x50 mm/kasan/kasan.c:302
>  memcpy include/linux/string.h:345 [inline]
>  rdma_bind_addr+0x13b/0x1d60 drivers/infiniband/core/cma.c:3361
>  ucma_bind_ip+0x10a/0x190 drivers/infiniband/core/ucma.c:639
>  ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1649
>  __vfs_write+0xef/0x970 fs/read_write.c:480
>  vfs_write+0x189/0x510 fs/read_write.c:544
>  SYSC_write fs/read_write.c:589 [inline]
>  SyS_write+0xef/0x220 fs/read_write.c:581
>  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>  entry_SYSCALL_64_after_hwframe+0x42/0xb7
> RIP: 0033:0x43fdd9
> RSP: 002b:00007ffc69ab4bb8 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fdd9
> RDX: 0000000000000090 RSI: 0000000020000080 RDI: 0000000000000003
> RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
> R10: 00000000004002c8 R11: 0000000000000217 R12: 0000000000401700
> R13: 0000000000401790 R14: 0000000000000000 R15: 0000000000000000
>
> The buggy address belongs to the page:
> page:ffffea0006bdc5c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
> flags: 0x2fffc0000000000()
> raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
> raw: 0000000000000000 ffffea0006bd0101 0000000000000000 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801af717900: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2
>  ffff8801af717980: f2 f2 f2 f2 f2 f2 04 f2 f2 f2 f3 f3 f3 f3 00 00
> > ffff8801af717a00: 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 f2 f2
>                                                              ^
>  ffff8801af717a80: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1
>  ffff8801af717b00: f1 f1 f1 00 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00
> ==================================================================
>
>
> ---
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