Re: KASAN: use-after-free Read in cma_acquire_dev

[Dmitry Vyukov]

On Sat, Jul 7, 2018 at 9:10 AM syzbot
<syzbot+908eac39ffdc39221032@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    fc36def997cf mm: teach dump_page() to correctly output poi..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1378110c400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=2ca6c7a31d407f86
> dashboard link: https://syzkaller.appspot.com/bug?extid=908eac39ffdc39221032
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+908eac39ffdc39221032@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> netlink: 4 bytes leftover after parsing attributes in process
> `syz-executor0'.
> QAT: Invalid ioctl
> capability: warning: `syz-executor0' uses deprecated v2 capabilities in a
> way that may be insecure
> ==================================================================
> BUG: KASAN: use-after-free in rdma_ip2gid include/rdma/ib_addr.h:143
> [inline]
> BUG: KASAN: use-after-free in cma_acquire_dev+0xe56/0xea0
> drivers/infiniband/core/cma.c:654
> Read of size 2 at addr ffff88019c561360 by task syz-executor2/8894


This seems to have been fixed by:

#syz fix: ucma: fix a use-after-free in ucma_resolve_ip()

So let's close the bug. Pile of neglected bug reports is not too useful.



> CPU: 1 PID: 8894 Comm: syz-executor2 Not tainted 4.18.0-rc3+ #131
> 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+0x1c9/0x2b4 lib/dump_stack.c:113
>   print_address_description+0x6c/0x20b mm/kasan/report.c:256
>   kasan_report_error mm/kasan/report.c:354 [inline]
>   kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
>   __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431
>   rdma_ip2gid include/rdma/ib_addr.h:143 [inline]
>   cma_acquire_dev+0xe56/0xea0 drivers/infiniband/core/cma.c:654
>   rdma_bind_addr+0x248/0x23b0 drivers/infiniband/core/cma.c:3388
>   cma_bind_addr drivers/infiniband/core/cma.c:2930 [inline]
>   rdma_resolve_addr+0x500/0x28a0 drivers/infiniband/core/cma.c:2942
>   ucma_resolve_ip+0x242/0x2a0 drivers/infiniband/core/ucma.c:711
>   ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1680
>   __vfs_write+0x117/0x9f0 fs/read_write.c:485
>   vfs_write+0x1f8/0x560 fs/read_write.c:549
>   ksys_write+0x101/0x260 fs/read_write.c:598
>   __do_sys_write fs/read_write.c:610 [inline]
>   __se_sys_write fs/read_write.c:607 [inline]
>   __x64_sys_write+0x73/0xb0 fs/read_write.c:607
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x455ba9
> Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fb04c987c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007fb04c9886d4 RCX: 0000000000455ba9
> RDX: 0000000000000048 RSI: 00000000200002c0 RDI: 0000000000000015
> RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000004c7f98 R14: 00000000004d4160 R15: 0000000000000000
>
> Allocated by task 8894:
>   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>   set_track mm/kasan/kasan.c:460 [inline]
>   kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
>   kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
>   kmalloc include/linux/slab.h:513 [inline]
>   kzalloc include/linux/slab.h:707 [inline]
>   __rdma_create_id+0xdf/0x720 drivers/infiniband/core/cma.c:780
>   ucma_create_id+0x399/0x9d0 drivers/infiniband/core/ucma.c:502
>   ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1680
>   __vfs_write+0x117/0x9f0 fs/read_write.c:485
>   vfs_write+0x1f8/0x560 fs/read_write.c:549
>   ksys_write+0x101/0x260 fs/read_write.c:598
>   __do_sys_write fs/read_write.c:610 [inline]
>   __se_sys_write fs/read_write.c:607 [inline]
>   __x64_sys_write+0x73/0xb0 fs/read_write.c:607
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 8905:
>   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>   set_track mm/kasan/kasan.c:460 [inline]
>   __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
>   kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>   __cache_free mm/slab.c:3498 [inline]
>   kfree+0xd9/0x260 mm/slab.c:3813
>   rdma_destroy_id+0x8cd/0xe60 drivers/infiniband/core/cma.c:1703
>   ucma_close+0x100/0x300 drivers/infiniband/core/ucma.c:1759
>   __fput+0x355/0x8b0 fs/file_table.c:209
>   ____fput+0x15/0x20 fs/file_table.c:243
>   task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
>   tracehook_notify_resume include/linux/tracehook.h:192 [inline]
>   exit_to_usermode_loop+0x313/0x370 arch/x86/entry/common.c:166
>   prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
>   syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
>   do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff88019c561340
>   which belongs to the cache kmalloc-2048 of size 2048
> The buggy address is located 32 bytes inside of
>   2048-byte region [ffff88019c561340, ffff88019c561b40)
> The buggy address belongs to the page:
> page:ffffea0006715800 count:1 mapcount:0 mapping:ffff8801da800c40
> index:0xffff88019c560240 compound_mapcount: 0
> flags: 0x2fffc0000008100(slab|head)
> raw: 02fffc0000008100 ffffea00066fb108 ffffea000670dc08 ffff8801da800c40
> raw: ffff88019c560240 ffff88019c560240 0000000100000002 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff88019c561200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff88019c561280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> > ffff88019c561300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>                                                         ^
>   ffff88019c561380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>   ffff88019c561400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>
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