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KASAN: slab-out-of-bounds Read in hci_extended_inquiry_result_evt
Status: fixed on 2020/09/09 05:22
Reported-by: syzbot+96761b8d6446f0a881b0@syzkaller.appspotmail.com
Fix commit: d91299b8382b Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()
First crash: 660d, last: 655d

Fix bisection: fixed by (bisect log) :
commit d91299b8382b129156708708d69876e753b9ade6
Author: Peilin Ye <yepeilin.cs@gmail.com>
Date: Fri Jul 10 16:09:15 2020 +0000

  Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in hci_extended_inquiry_result_evt C 16 658d 685d 17/22 fixed on 2020/09/16 22:51
linux-4.19 KASAN: slab-out-of-bounds Read in hci_extended_inquiry_result_evt C done 6 655d 689d 1/1 fixed on 2020/09/09 05:22

Sample crash report:
audit: type=1400 audit(1596368109.832:8): avc:  denied  { execmem } for  pid=6354 comm="syz-executor705" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy include/net/bluetooth/bluetooth.h:233 [inline]
BUG: KASAN: slab-out-of-bounds in hci_extended_inquiry_result_evt.isra.0+0x17b/0x4f0 net/bluetooth/hci_event.c:3841
Read of size 6 at addr ffff888091817248 by task kworker/u5:0/1202

CPU: 0 PID: 1202 Comm: kworker/u5:0 Not tainted 4.14.191-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci0 hci_rx_work
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report+0x6f/0x7b mm/kasan/report.c:409
 memcpy+0x20/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:372 [inline]
 bacpy include/net/bluetooth/bluetooth.h:233 [inline]
 hci_extended_inquiry_result_evt.isra.0+0x17b/0x4f0 net/bluetooth/hci_event.c:3841
 hci_event_packet+0xcfb/0x7c7a net/bluetooth/hci_event.c:5376
 hci_rx_work+0x3e6/0x970 net/bluetooth/hci_core.c:4244
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 6355:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc_node mm/slab.c:3682 [inline]
 __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696
 __kmalloc_reserve net/core/skbuff.c:137 [inline]
 __alloc_skb+0x96/0x510 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:980 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:336 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:180 [inline]
 vhci_write+0xb1/0x420 drivers/bluetooth/hci_vhci.c:299
 call_write_iter include/linux/fs.h:1778 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x44c/0x630 fs/read_write.c:482
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 4429:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 kernfs_fop_release+0x10e/0x180 fs/kernfs/file.c:783
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff888091817040
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes to the right of
 512-byte region [ffff888091817040, ffff888091817240)
The buggy address belongs to the page:
page:ffffea00024605c0 count:1 mapcount:0 mapping:ffff888091817040 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff888091817040 0000000000000000 0000000100000006
raw: ffffea000248eae0 ffffea0002673060 ffff88812fe52940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888091817100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888091817180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888091817200: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                              ^
 ffff888091817280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff888091817300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/08/02 11:36 linux-4.14.y 7f2c5eb458b8 96dd3623 .config log report syz C
ci2-linux-4-14 2020/08/07 18:29 linux-4.14.y 14b58326976d 28ac5c9e .config log report
ci2-linux-4-14 2020/08/07 14:38 linux-4.14.y 14b58326976d 28ac5c9e .config log report
ci2-linux-4-14 2020/08/02 12:18 linux-4.14.y 7f2c5eb458b8 96dd3623 .config log report
ci2-linux-4-14 2020/08/02 11:18 linux-4.14.y 7f2c5eb458b8 96dd3623 .config log report