Re: ath9k rate control API abuse

Re: ath9k rate control API abuse

[Vasanthakumar Thiagarajan]

Johannes Berg wrote:
> Hi,
>
> I decided to review ath9k as well wrt. the RC algorithm (Intel stuff
> coming later). It doesn't exactly have the same deficiencies as the
> Intel drivers, but it's still very very very fragile.
>
> For example, you can make it crash with a double-free like this:
>
> # iwconfig wlan0 frag 300
>
> [  206.647389] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> [  206.647791] BUG kmalloc-96: Object already free
> [  206.648006] ------------------------------------------------------=
-----------------------
> [  206.648009]=20
> [  206.648504] INFO: Allocated in .ath_get_rate+0xa8/0x9d0 [ath9k] ag=
e=3D0 cpu=3D1 pid=3D4447
> [  206.648893] INFO: Freed in .ath_tx_status+0x368/0x3b4 [ath9k] age=3D=
0 cpu=3D0 pid=3D0
> [  206.649238] INFO: Slab 0xc00000001c5f49c0 objects=3D24 used=3D10 f=
p=3D0xc00000020fe1a9d8 flags=3D0x00c3
> [  206.649643] INFO: Object 0xc00000020fe1a9d8 @offset=3D2520 fp=3D0x=
c00000020fe1aa80
> [  206.649646]=20
> [  206.650052] Bytes b4 0xc00000020fe1a9c8:  00 00 00 00 ff fd f3 45 =
5a 5a 5a 5a 5a 5a 5a 5a ....=EF=BF=BD=EF=BF=BD=EF=BF=BDEZZZZZZZZ
> [  206.650693]   Object 0xc00000020fe1a9d8:  6b 6b 6b 6b 6b 6b 6b 6b =
6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> [  206.651333]   Object 0xc00000020fe1a9e8:  6b 6b 6b 6b 6b 6b 6b 6b =
6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
> [  206.651972]   Object 0xc00000020fe1a9f8:  3c 13 f2 77 00 00 00 8f =
00 2a 00 00 00 01 00 28 <.=EF=BF=BDw.....*.....(
> [  206.652612]   Object 0xc00000020fe1aa08:  26 80 27 26 80 00 00 00 =
00 00 00 00 00 00 00 00 &.'&............
> [  206.653252]   Object 0xc00000020fe1aa18:  2a 80 26 27 80 80 80 80 =
80 80 80 80 00 00 00 01 *.&'............
> [  206.653892]   Object 0xc00000020fe1aa28:  00 00 00 00 6b 6b 6b 6b =
6b 6b 6b 6b 6b 6b 6b a5 ....kkkkkkkkkkk=EF=BF=BD
> [  206.654531]  Redzone 0xc00000020fe1aa38:  bb bb bb bb bb bb bb bb =
                        =EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD       =20
> [  206.655169]  Padding 0xc00000020fe1aa78:  5a 5a 5a 5a 5a 5a 5a 5a =
                        ZZZZZZZZ       =20
> [  206.655806] Call Trace:
> [  206.655930] [c00000000080b050] [c00000000000f880] .show_stack+0x6c=
/0x174 (unreliable)
> [  206.656326] [c00000000080b100] [c0000000000e7880] .print_trailer+0=
x150/0x178
> [  206.656672] [c00000000080b1a0] [c0000000000e909c] .__slab_free+0x3=
b0/0x4c4
> [  206.657009] [c00000000080b260] [c0000000000eab30] .kfree+0x150/0x1=
b0
> [  206.657344] [c00000000080b310] [d00000000017eda8] .ath_tx_status+0=
x368/0x3b4 [ath9k]
> [  206.657760] [c00000000080b400] [d0000000001b9370] .ieee80211_tx_st=
atus+0x240/0x5e8 [mac80211]
> [  206.658192] [c00000000080b4c0] [d0000000001767f0] .ath_tx_complete=
+0xfc/0x148 [ath9k]
> [  206.658593] [c00000000080b570] [d000000000178ec8] .ath_tx_complete=
_buf+0xf4/0x168 [ath9k]
> [  206.659010] [c00000000080b630] [d00000000017c4a8] .ath_tx_tasklet+=
0x4d4/0x5dc [ath9k]
> [  206.659413] [c00000000080b750] [d000000000181394] .ath9k_tasklet+0=
x8c/0xbc [ath9k]
> [  206.659783] [c00000000080b7e0] [c0000000000551dc] .tasklet_action+=
0x14c/0x244
> [  206.660132] [c00000000080b890] [c0000000000560cc] .__do_softirq+0x=
d8/0x1c4
> [  206.660469] [c00000000080b940] [c00000000000c2b8] .do_softirq+0x5c=
/0xb8
> [  206.660794] [c00000000080b9c0] [c000000000055b08] .irq_exit+0x74/0=
xe0
> [  206.661112] [c00000000080ba40] [c00000000000c41c] .do_IRQ+0x108/0x=
14c
> [  206.661430] [c00000000080bad0] [c000000000004794] hardware_interru=
pt_entry+0x1c/0x20
> [  206.661810] --- Exception: 501 at .cpu_idle+0x118/0x200
> [  206.661812]     LR =3D .cpu_idle+0x118/0x200
> [  206.662252] [c00000000080bdc0] [c000000000011ec8] .cpu_idle+0xd0/0=
x200 (unreliable)
> [  206.662640] [c00000000080be60] [c0000000003ee8d4] .rest_init+0x8c/=
0xa4
> [  206.662964] [c00000000080bee0] [c000000000587bc0] .start_kernel+0x=
4a0/0x4c8
> [  206.663305] [c00000000080bf90] [c000000000007568] .start_here_comm=
on+0x3c/0x54
> [  206.663657] FIX kmalloc-96: Object at 0xc00000020fe1a9d8 not freed
>
> FAIL.
>
> This tries to free the ath_tx_info_priv which you've copied into the =
tx
> info at rate control time, that's not intended, and it got duplicated=
 to
> each fragment. Oops. You're lucky it doesn't normally oops, a small
> change to struct ieee80211_tx_info could make it oops all the time. S=
ay
> changing the positions of control.vif and control.key.
>
> johannes
>  =20

Johannes,

Thanks for the bug report and comments.  This private structure was
mainly introduced for
multirate support. Since now tx_info has most of the information that w=
e
need for
rate control this private structure can be nuked. I will clean this up.

Vasanth

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ath9k rate control API abuse

[Johannes Berg]

[-- Attachment #1: Type: text/plain, Size: 4200 bytes --]

Hi,

I decided to review ath9k as well wrt. the RC algorithm (Intel stuff
coming later). It doesn't exactly have the same deficiencies as the
Intel drivers, but it's still very very very fragile.

For example, you can make it crash with a double-free like this:

# iwconfig wlan0 frag 300

[  206.647389] =============================================================================
[  206.647791] BUG kmalloc-96: Object already free
[  206.648006] -----------------------------------------------------------------------------
[  206.648009] 
[  206.648504] INFO: Allocated in .ath_get_rate+0xa8/0x9d0 [ath9k] age=0 cpu=1 pid=4447
[  206.648893] INFO: Freed in .ath_tx_status+0x368/0x3b4 [ath9k] age=0 cpu=0 pid=0
[  206.649238] INFO: Slab 0xc00000001c5f49c0 objects=24 used=10 fp=0xc00000020fe1a9d8 flags=0x00c3
[  206.649643] INFO: Object 0xc00000020fe1a9d8 @offset=2520 fp=0xc00000020fe1aa80
[  206.649646] 
[  206.650052] Bytes b4 0xc00000020fe1a9c8:  00 00 00 00 ff fd f3 45 5a 5a 5a 5a 5a 5a 5a 5a ....���EZZZZZZZZ
[  206.650693]   Object 0xc00000020fe1a9d8:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
[  206.651333]   Object 0xc00000020fe1a9e8:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
[  206.651972]   Object 0xc00000020fe1a9f8:  3c 13 f2 77 00 00 00 8f 00 2a 00 00 00 01 00 28 <.�w.....*.....(
[  206.652612]   Object 0xc00000020fe1aa08:  26 80 27 26 80 00 00 00 00 00 00 00 00 00 00 00 &.'&............
[  206.653252]   Object 0xc00000020fe1aa18:  2a 80 26 27 80 80 80 80 80 80 80 80 00 00 00 01 *.&'............
[  206.653892]   Object 0xc00000020fe1aa28:  00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 ....kkkkkkkkkkk�
[  206.654531]  Redzone 0xc00000020fe1aa38:  bb bb bb bb bb bb bb bb                         ��������        
[  206.655169]  Padding 0xc00000020fe1aa78:  5a 5a 5a 5a 5a 5a 5a 5a                         ZZZZZZZZ        
[  206.655806] Call Trace:
[  206.655930] [c00000000080b050] [c00000000000f880] .show_stack+0x6c/0x174 (unreliable)
[  206.656326] [c00000000080b100] [c0000000000e7880] .print_trailer+0x150/0x178
[  206.656672] [c00000000080b1a0] [c0000000000e909c] .__slab_free+0x3b0/0x4c4
[  206.657009] [c00000000080b260] [c0000000000eab30] .kfree+0x150/0x1b0
[  206.657344] [c00000000080b310] [d00000000017eda8] .ath_tx_status+0x368/0x3b4 [ath9k]
[  206.657760] [c00000000080b400] [d0000000001b9370] .ieee80211_tx_status+0x240/0x5e8 [mac80211]
[  206.658192] [c00000000080b4c0] [d0000000001767f0] .ath_tx_complete+0xfc/0x148 [ath9k]
[  206.658593] [c00000000080b570] [d000000000178ec8] .ath_tx_complete_buf+0xf4/0x168 [ath9k]
[  206.659010] [c00000000080b630] [d00000000017c4a8] .ath_tx_tasklet+0x4d4/0x5dc [ath9k]
[  206.659413] [c00000000080b750] [d000000000181394] .ath9k_tasklet+0x8c/0xbc [ath9k]
[  206.659783] [c00000000080b7e0] [c0000000000551dc] .tasklet_action+0x14c/0x244
[  206.660132] [c00000000080b890] [c0000000000560cc] .__do_softirq+0xd8/0x1c4
[  206.660469] [c00000000080b940] [c00000000000c2b8] .do_softirq+0x5c/0xb8
[  206.660794] [c00000000080b9c0] [c000000000055b08] .irq_exit+0x74/0xe0
[  206.661112] [c00000000080ba40] [c00000000000c41c] .do_IRQ+0x108/0x14c
[  206.661430] [c00000000080bad0] [c000000000004794] hardware_interrupt_entry+0x1c/0x20
[  206.661810] --- Exception: 501 at .cpu_idle+0x118/0x200
[  206.661812]     LR = .cpu_idle+0x118/0x200
[  206.662252] [c00000000080bdc0] [c000000000011ec8] .cpu_idle+0xd0/0x200 (unreliable)
[  206.662640] [c00000000080be60] [c0000000003ee8d4] .rest_init+0x8c/0xa4
[  206.662964] [c00000000080bee0] [c000000000587bc0] .start_kernel+0x4a0/0x4c8
[  206.663305] [c00000000080bf90] [c000000000007568] .start_here_common+0x3c/0x54
[  206.663657] FIX kmalloc-96: Object at 0xc00000020fe1a9d8 not freed

FAIL.

This tries to free the ath_tx_info_priv which you've copied into the tx
info at rate control time, that's not intended, and it got duplicated to
each fragment. Oops. You're lucky it doesn't normally oops, a small
change to struct ieee80211_tx_info could make it oops all the time. Say
changing the positions of control.vif and control.key.

johannes

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Re: ath9k rate control API abuse

[Johannes Berg]

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On Fri, 2008-10-10 at 11:10 +0200, Johannes Berg wrote:
> Hi,
> 
> I decided to review ath9k as well wrt. the RC algorithm (Intel stuff
> coming later). It doesn't exactly have the same deficiencies as the
> Intel drivers, but it's still very very very fragile.
> 
> For example, you can make it crash with a double-free like this:
> 
> # iwconfig wlan0 frag 300

As a band-aid, you can provide the set_frag_threshold function and have
it do nothing.

johannes

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Re: ath9k rate control API abuse

[Johannes Berg]

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On Fri, 2008-10-10 at 14:00 +0530, Vasanthakumar Thiagarajan wrote:

> Thanks for the bug report and comments.  This private structure was
> mainly introduced for
> multirate support. Since now tx_info has most of the information that we
> need for
> rate control this private structure can be nuked. I will clean this up.

Wait a minute. We're about to post patches that revamp it again and that
will be much easier for you too.

johannes

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