KASAN reported an error while executing accept-reust.t testcase

[lizetao <lizetao1@huawei.com>]

Hi all,

When I run the testcase liburing/accept-reust.t with CONFIG_KASAN=y and CONFIG_KASAN_EXTRA_INFO=y, I got
a error reported by KASAN:

Unable to handle kernel paging request at virtual address 00000c6455008008
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=00000001104c5000
[00000c6455008008] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 6 UID: 0 PID: 352 Comm: kworker/u128:5 Not tainted 6.13.0-rc6-g0a2cb793507d #5
Hardware name: linux,dummy-virt (DT)
Workqueue: iou_exit io_ring_exit_work
pstate: 10000005 (nzcV daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __kasan_mempool_unpoison_object+0x38/0x170
lr : io_netmsg_cache_free+0x8c/0x180
sp : ffff800083297a90
x29: ffff800083297a90 x28: ffffd4d7f67e88e4 x27: 0000000000000003
x26: 1fffe5958011502e x25: ffff2cabff976c18 x24: 1fffe5957ff2ed83
x23: ffff2cabff976c10 x22: 00000c6455008000 x21: 0002992540200001
x20: 0000000000000000 x19: 00000c6455008000 x18: 00000000489683f8
x17: ffffd4d7f68006ac x16: ffffd4d7f67eb3e0 x15: ffffd4d7f67e88e4
x14: ffffd4d7f766deac x13: ffffd4d7f6619030 x12: ffff7a9b012e3e26
x11: 1ffffa9b012e3e25 x10: ffff7a9b012e3e25 x9 : ffffd4d7f766debc
x8 : ffffd4d80971f128 x7 : 0000000000000001 x6 : 00008564fed1c1db
x5 : ffffd4d80971f128 x4 : ffff7a9b012e3e26 x3 : ffff2cabff976c00
x2 : ffffc1ffc0000000 x1 : 0000000000000000 x0 : 0002992540200001
Call trace:
 __kasan_mempool_unpoison_object+0x38/0x170 (P)
 io_netmsg_cache_free+0x8c/0x180
 io_ring_exit_work+0xd4c/0x13a0
 process_one_work+0x52c/0x1000
 worker_thread+0x830/0xdc0
 kthread+0x2bc/0x348
 ret_from_fork+0x10/0x20
Code: aa0003f5 aa0103f4 8b131853 aa1303f6 (f9400662) 
---[ end trace 0000000000000000 ]---


I preliminary analyzed the accept and connect code logic. In the accept-reuse.t testcase, kmsg->free_iov is
not used, so when calling io_netmsg_cache_free(), the kasan_mempool_unpoison_object(kmsg->free_iov...) path
should not be executed.


I used the hardware watchpoint to capture the first scene of modifying kmsg->free_iov:

Thread 3 hit Hardware watchpoint 7: *0xffff0000ebfc5410
Old value = 0
New value = -211812350
kasan_set_track (stack=<optimized out>, track=<optimized out>) at ./arch/arm64/include/asm/current.h:21
21		return (struct task_struct *)sp_el0;

# bt
kasan_set_track
kasan_save_track
kasan_save_free_info
poison_slab_object
__kasan_mempool_poison_object
kasan_mempool_poison_object
io_alloc_cache_put
io_netmsg_recycle
io_req_msg_cleanup
io_connect
io_issue_sqe
io_queue_sqe
io_req_task_submit
...


It's a bit strange. It was modified by KASAN. I can't understand this.
Maybe I missed something? Please let me know. Thanks.

---
Li Zetao