linux-hardening - Re: [syzbot] BUG: bad usercopy in io_openat2

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Date:   Sun, 12 Feb 2023 08:04:26 -0800
From:   syzbot <syzbot+cdd9922704fc75e03ffc@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, asml.silence@...il.com,
        io-uring@...r.kernel.org, kees@...nel.org, keescook@...omium.org,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] BUG: bad usercopy in io_openat2_prep

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: bad usercopy in io_openat2_prep

usercopy: Kernel memory overwrite attempt detected to SLUB object 'pid' (offset 24, size 24)!
------------[ cut here ]------------
kernel BUG at mm/usercopy.c:102!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4995 Comm: syz-executor.0 Not tainted 6.2.0-rc6-syzkaller-00050-gfbe870a72fd1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : usercopy_abort+0x90/0x94
lr : usercopy_abort+0x90/0x94
sp : ffff800012dd3be0
x29: ffff800012dd3bf0 x28: 000000000000001c x27: ffff0000d0e13400
x26: 00000000200000c0 x25: ffff80000cf51000 x24: fffffc0000000000
x23: 05ffc00000000200 x22: fffffc0003108280 x21: ffff0000c420a118
x20: 0000000000000000 x19: 0000000000000018 x18: 0000000000000000
x17: 0000000000000000 x16: ffff0000d0e13df8 x15: ffff80000dbd1118
x14: ffff0000d0e13400 x13: 00000000ffffffff x12: ffff0000d0e13400
x11: ff808000081bd5b0 x10: 0000000000000000 x9 : 4c3aa38d2e853f00
x8 : 4c3aa38d2e853f00 x7 : ffff800008162dbc x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0001fefbff08 x1 : 0000000100000000 x0 : 000000000000005d
Call trace:
 usercopy_abort+0x90/0x94
 __check_heap_object+0xa8/0x100
 __check_object_size+0x208/0x6b8
 io_openat2_prep+0xcc/0x2f0
 io_submit_sqes+0x330/0xba8
 __arm64_sys_io_uring_enter+0x168/0x9b0
 invoke_syscall+0x64/0x178
 el0_svc_common+0xbc/0x180
 do_el0_svc+0x48/0x150
 el0_svc+0x58/0x14c
 el0t_64_sync_handler+0x84/0xf0
 el0t_64_sync+0x190/0x194
Code: 911d2800 aa0903e1 f90003e8 94e6d3da (d4210000) 
---[ end trace 0000000000000000 ]---


Tested on:

commit:         fbe870a7 io_uring,audit: don't log IORING_OP_MADVISE
git tree:       https://git.kernel.dk/linux.git for-6.3/io_uring
console output: https://syzkaller.appspot.com/x/log.txt?x=17241257480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=22fc000172595f28
dashboard link: https://syzkaller.appspot.com/bug?extid=cdd9922704fc75e03ffc
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

Note: no patches were applied.