Hi, > -----Original Message----- > From: Jens Axboe <axboe@xxxxxxxxx> > Sent: Sunday, January 12, 2025 1:13 AM > To: lizetao <lizetao1@xxxxxxxxxx>; io-uring <io-uring@xxxxxxxxxxxxxxx> > Cc: Pavel Begunkov <asml.silence@xxxxxxxxx> > Subject: Re: KASAN reported an error while executing accept-reust.t testcase > > On 1/11/25 7:07 AM, lizetao wrote: > > 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: > > Looks more like you get KASAN crashing... > > > 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. > > Looks like KASAN with the extra info ends up writing to io_async_msghdr- > >free_iov somehow. No idea... For the test case in question, ->free_iov should > be NULL when initially allocated, and the io_uring code isn't storing to it. Yet > it's non-NULL when you later go and free it, after calling > kasan_mempool_poison_object(). I also think so and would Juntong and Ryabinin or others KASAN developers be interested In this problem? +CC juntong.deng@xxxxxxxxxxx, ryabinin.a.a@xxxxxxxxx and kasan-dev@xxxxxxxxxxxxxxxx Thank you so mush. > > -- > Jens Axboe --- Li Zetao
