lkml.org 
[lkml]   [2022]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: A slab-out-of-bounds Read bug in __htab_map_lookup_and_delete_batch
Ok, I just reproduce the issue with the latest bpf-next tree.

On Fri, Jan 7, 2022 at 9:19 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 12/29/21 7:23 PM, butt3rflyh4ck wrote:
> > Hi, the attachment is a reproducer. Enjoy it.
> >
> > Regards,
> > butt3rflyh4ck.
> >
> >
> > On Thu, Dec 30, 2021 at 10:23 AM Alexei Starovoitov
> > <alexei.starovoitov@gmail.com> wrote:
> >>
> >> On Wed, Dec 29, 2021 at 2:10 AM butt3rflyh4ck
> >> <butterflyhuangxx@gmail.com> wrote:
> >>>
> >>> Hi, there is a slab-out-bounds Read bug in
> >>> __htab_map_lookup_and_delete_batch in kernel/bpf/hashtab.c
> >>> and I reproduce it in linux-5.16.rc7(upstream) and latest linux-5.15.11.
> >>>
> >>> #carsh log
> >>> [ 166.945208][ T6897]
> >>> ==================================================================
> >>> [ 166.947075][ T6897] BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x87/0xb0
> >>> [ 166.948612][ T6897] Read of size 49 at addr ffff88801913f800 by
> >>> task __htab_map_look/6897
> >>> [ 166.950406][ T6897]
> >>> [ 166.950890][ T6897] CPU: 1 PID: 6897 Comm: __htab_map_look Not
> >>> tainted 5.16.0-rc7+ #30
> >>> [ 166.952521][ T6897] Hardware name: QEMU Standard PC (i440FX + PIIX,
> >>> 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
> >>> [ 166.954562][ T6897] Call Trace:
> >>> [ 166.955268][ T6897] <TASK>
> >>> [ 166.955918][ T6897] dump_stack_lvl+0x57/0x7d
> >>> [ 166.956875][ T6897] print_address_description.constprop.0.cold+0x93/0x347
> >>> [ 166.958411][ T6897] ? _copy_to_user+0x87/0xb0
> >>> [ 166.959356][ T6897] ? _copy_to_user+0x87/0xb0
> >>> [ 166.960272][ T6897] kasan_report.cold+0x83/0xdf
> >>> [ 166.961196][ T6897] ? _copy_to_user+0x87/0xb0
> >>> [ 166.962053][ T6897] kasan_check_range+0x13b/0x190
> >>> [ 166.962978][ T6897] _copy_to_user+0x87/0xb0
> >>> [ 166.964340][ T6897] __htab_map_lookup_and_delete_batch+0xdc2/0x1590
> >>> [ 166.965619][ T6897] ? htab_lru_map_update_elem+0xe70/0xe70
> >>> [ 166.966732][ T6897] bpf_map_do_batch+0x1fa/0x460
> >>> [ 166.967619][ T6897] __sys_bpf+0x99a/0x3860
> >>> [ 166.968443][ T6897] ? bpf_link_get_from_fd+0xd0/0xd0
> >>> [ 166.969393][ T6897] ? rcu_read_lock_sched_held+0x9c/0xd0
> >>> [ 166.970425][ T6897] ? lock_acquire+0x1ab/0x520
> >>> [ 166.971284][ T6897] ? find_held_lock+0x2d/0x110
> >>> [ 166.972208][ T6897] ? rcu_read_lock_sched_held+0x9c/0xd0
> >>> [ 166.973139][ T6897] ? rcu_read_lock_bh_held+0xb0/0xb0
> >>> [ 166.974096][ T6897] __x64_sys_bpf+0x70/0xb0
> >>> [ 166.974903][ T6897] ? syscall_enter_from_user_mode+0x21/0x70
> >>> [ 166.976077][ T6897] do_syscall_64+0x35/0xb0
> >>> [ 166.976889][ T6897] entry_SYSCALL_64_after_hwframe+0x44/0xae
> >>> [ 166.978027][ T6897] RIP: 0033:0x450f0d
> >>>
> >>>
> >>> In hashtable, if the elements' keys have the same jhash() value, the
> >>> elements will be put into the same bucket.
> >>> By putting a lot of elements into a single bucket, the value of
> >>> bucket_size can be increased to overflow.
> >>> but also we can increase bucket_cnt to out of bound Read.
>
> I tried the attachment (reproducer) and cannot reproduce the issue
> with latest bpf-next tree.
> My config has kasan enabled. Could you send the matching .config file
> as well so I could reproduce?
>
> >>
> >> Can you be more specific?
> >> If you can send a patch with a fix it would be even better.
> >>
> >>> the out of bound Read in __htab_map_lookup_and_delete_batch code:
> >>> ```
> >>> ...
> >>> if (bucket_cnt && (copy_to_user(ukeys + total * key_size, keys,
> >>> key_size * bucket_cnt) ||
> >>> copy_to_user(uvalues + total * value_size, values,
> >>> value_size * bucket_cnt))) {
> >>> ret = -EFAULT;
> >>> goto after_loop;
> >>> }
> >>> ...
> >>> ```
> >>>
> >>> Regards,
> >>> butt3rflyh4ck.
> >>>
> >>>
> >>> --
> >>> Active Defense Lab of Venustech
> >
> >
> >



--
Active Defense Lab of Venustech
[unhandled content-type:application/octet-stream]
\
 
 \ /
  Last update: 2022-01-07 04:26    [W:1.216 / U:0.504 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site