Re: [BUG][5.20] refcount_t: underflow; use-after-free

From: Christian König
Date: Mon Aug 15 2022 - 06:58:35 EST

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Am 15.08.22 um 12:55 schrieb Melissa Wen:

On 08/14, Maíra Canal wrote:

Hi Mikhail

Looks like this use-after-free problem was introduced on
90af0ca047f3049c4b46e902f432ad6ef1e2ded6. Checking this patch it seems
like: if amdgpu_cs_vm_handling return r != 0, then it will unlock
bo_list_mutex inside the function amdgpu_cs_vm_handling and again on
amdgpu_cs_parser_fini.

Maybe the following patch will help:

---
From 71d718c0f53a334bb59bcd5dabd29bbe92c724af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ADra=20Canal?= <mairacanal@xxxxxxxxxx>
Date: Sun, 14 Aug 2022 21:12:24 -0300
Subject: [PATCH] drm/amdgpu: Fix use-after-free on amdgpu_bo_list mutex
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes: 90af0ca047f3 ("drm/amdgpu: Protect the amdgpu_bo_list list with a
mutex v2")
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@xxxxxxxxx>
Signed-off-by: Maíra Canal <mairacanal@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index d8f1335bc68f..a7fce7b14321 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -837,17 +837,14 @@ static int amdgpu_cs_vm_handling(struct
amdgpu_cs_parser *p)
continue;

r = amdgpu_vm_bo_update(adev, bo_va, false);
- if (r) {
- mutex_unlock(&p->bo_list->bo_list_mutex);
+ if (r)
return r;
- }

r = amdgpu_sync_fence(&p->job->sync, bo_va->last_pt_update);
- if (r) {
- mutex_unlock(&p->bo_list->bo_list_mutex);
+ if (r)
return r;
- }
}
+ mutex_unlock(&p->bo_list->bo_list_mutex);

I think we don't need to unlock the bo_list_mutex here. If return != 0
amdgpu_cs_parser_fini() will unlock it; otherwise, amdgpu_cs_submit()
unlocks it in the end.

Yeah, exactly that.

Apart from that the patch looks good to me. We moved the mutex unlocking around a few times during review. Probably just a fallout from that.

Thanks for fixing this,
Christian.

BR,

Melissa

r = amdgpu_vm_handle_moved(adev, vm);
if (r)
--
2.37.1
---
Best Regards,
- Maíra Canal

On 8/14/22 18:11, Mikhail Gavrilov wrote:

Hi folks.
Joined testing 5.20 today (7ebfc85e2cd7).
I encountered a frequently GPU freeze, after which a message appears
in the kernel logs:
[ 220.280990] ------------[ cut here ]------------
[ 220.281000] refcount_t: underflow; use-after-free.
[ 220.281019] WARNING: CPU: 1 PID: 3746 at lib/refcount.c:28
refcount_warn_saturate+0xba/0x110
[ 220.281029] Modules linked in: uinput rfcomm snd_seq_dummy
snd_hrtimer nft_objref nf_conntrack_netbios_ns nf_conntrack_broadcast
nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet
nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat
nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink
qrtr bnep sunrpc snd_seq_midi snd_seq_midi_event vfat intel_rapl_msr
fat intel_rapl_common snd_hda_codec_realtek mt76x2u
snd_hda_codec_generic snd_hda_codec_hdmi mt76x2_common iwlmvm
mt76x02_usb edac_mce_amd mt76_usb snd_hda_intel snd_intel_dspcfg
mt76x02_lib snd_intel_sdw_acpi snd_usb_audio snd_hda_codec mt76
kvm_amd uvcvideo mac80211 snd_hda_core btusb eeepc_wmi snd_usbmidi_lib
videobuf2_vmalloc videobuf2_memops kvm btrtl snd_rawmidi asus_wmi
snd_hwdep videobuf2_v4l2 btbcm iwlwifi ledtrig_audio libarc4 btintel
snd_seq videobuf2_common sparse_keymap btmtk irqbypass videodev
snd_seq_device joydev xpad iwlmei platform_profile bluetooth
ff_memless snd_pcm mc rapl
[ 220.281185] video snd_timer cfg80211 wmi_bmof snd pcspkr soundcore
k10temp i2c_piix4 rfkill mei asus_ec_sensors acpi_cpufreq zram
hid_logitech_hidpp amdgpu igb dca drm_ttm_helper ttm crct10dif_pclmul
iommu_v2 crc32_pclmul gpu_sched crc32c_intel ucsi_ccg drm_buddy nvme
typec_ucsi ghash_clmulni_intel drm_display_helper ccp nvme_core typec
sp5100_tco cec wmi ip6_tables ip_tables fuse
[ 220.281258] Unloaded tainted modules: amd64_edac():1 amd64_edac():1
amd64_edac():1 amd64_edac():1 amd64_edac():1 amd64_edac():1
amd64_edac():1 amd64_edac():1 amd64_edac():1 pcc_cpufreq():1
amd64_edac():1 pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1
pcc_cpufreq():1 amd64_edac():1 amd64_edac():1 pcc_cpufreq():1
amd64_edac():1 pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1
pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1 pcc_cpufreq():1
pcc_cpufreq():1 amd64_edac():1 pcc_cpufreq():1 amd64_edac():1
pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1 amd64_edac():1
pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1 amd64_edac():1
pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1 amd64_edac():1
pcc_cpufreq():1 amd64_edac():1 pcc_cpufreq():1 pcc_cpufreq():1
amd64_edac():1 pcc_cpufreq():1 amd64_edac():1 amd64_edac():1
pcc_cpufreq():1 amd64_edac():1 pcc_cpufreq():1 amd64_edac():1
pcc_cpufreq():1 pcc_cpufreq():1 amd64_edac():1 pcc_cpufreq():1
amd64_edac():1 pcc_cpufreq():1 pcc_cpufreq():1 pcc_cpufreq():1
[ 220.281388] pcc_cpufreq():1 fjes():1 pcc_cpufreq():1 fjes():1
fjes():1 fjes():1 fjes():1 fjes():1 fjes():1 fjes():1
[ 220.281415] CPU: 1 PID: 3746 Comm: chrome:cs0 Tainted: G W L -------
--- 5.20.0-0.rc0.20220812git7ebfc85e2cd7.10.fc38.x86_64 #1
[ 220.281421] Hardware name: System manufacturer System Product
Name/ROG STRIX X570-I GAMING, BIOS 4403 04/27/2022
[ 220.281426] RIP: 0010:refcount_warn_saturate+0xba/0x110
[ 220.281431] Code: 01 01 e8 79 4a 6f 00 0f 0b e9 42 47 a5 00 80 3d de
7e be 01 00 75 85 48 c7 c7 f8 98 8e 98 c6 05 ce 7e be 01 01 e8 56 4a
6f 00 <0f> 0b e9 1f 47 a5 00 80 3d b9 7e be 01 00 0f 85 5e ff ff ff 48
c7
[ 220.281437] RSP: 0018:ffffb4b0d18d7a80 EFLAGS: 00010282
[ 220.281443] RAX: 0000000000000026 RBX: 0000000000000003 RCX: 0000000000000000
[ 220.281448] RDX: 0000000000000001 RSI: ffffffff988d06dc RDI: 00000000ffffffff
[ 220.281452] RBP: 00000000ffffffff R08: 0000000000000000 R09: ffffb4b0d18d7930
[ 220.281457] R10: 0000000000000003 R11: ffffa0672e2fffe8 R12: ffffa058ca360400
[ 220.281461] R13: ffffa05846c50a18 R14: 00000000fffffe00 R15: 0000000000000003
[ 220.281465] FS: 00007f82683e06c0(0000) GS:ffffa066e2e00000(0000)
knlGS:0000000000000000
[ 220.281470] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 220.281475] CR2: 00003590005cc000 CR3: 00000001fca46000 CR4: 0000000000350ee0
[ 220.281480] Call Trace:
[ 220.281485] <TASK>
[ 220.281490] amdgpu_cs_ioctl+0x4e2/0x2070 [amdgpu]
[ 220.281806] ? amdgpu_cs_find_mapping+0xe0/0xe0 [amdgpu]
[ 220.282028] drm_ioctl_kernel+0xa4/0x150
[ 220.282043] drm_ioctl+0x21f/0x420
[ 220.282053] ? amdgpu_cs_find_mapping+0xe0/0xe0 [amdgpu]
[ 220.282275] ? lock_release+0x14f/0x460
[ 220.282282] ? _raw_spin_unlock_irqrestore+0x30/0x60
[ 220.282290] ? _raw_spin_unlock_irqrestore+0x30/0x60
[ 220.282297] ? lockdep_hardirqs_on+0x7d/0x100
[ 220.282305] ? _raw_spin_unlock_irqrestore+0x40/0x60
[ 220.282317] amdgpu_drm_ioctl+0x4a/0x80 [amdgpu]
[ 220.282534] __x64_sys_ioctl+0x90/0xd0
[ 220.282545] do_syscall_64+0x5b/0x80
[ 220.282551] ? futex_wake+0x6c/0x150
[ 220.282568] ? lock_is_held_type+0xe8/0x140
[ 220.282580] ? do_syscall_64+0x67/0x80
[ 220.282585] ? lockdep_hardirqs_on+0x7d/0x100
[ 220.282592] ? do_syscall_64+0x67/0x80
[ 220.282597] ? do_syscall_64+0x67/0x80
[ 220.282602] ? lockdep_hardirqs_on+0x7d/0x100
[ 220.282609] entry_SYSCALL_64_after_hwframe+0x63/0xcd
[ 220.282616] RIP: 0033:0x7f8282a4f8bf
[ 220.282639] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10
00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00
0f 05 <89> c2 3d 00 f0 ff ff 77 18 48 8b 44 24 18 64 48 2b 04 25 28 00
00
[ 220.282644] RSP: 002b:00007f82683df410 EFLAGS: 00000246 ORIG_RAX:
0000000000000010
[ 220.282651] RAX: ffffffffffffffda RBX: 00007f82683df588 RCX: 00007f8282a4f8bf
[ 220.282655] RDX: 00007f82683df4d0 RSI: 00000000c0186444 RDI: 0000000000000018
[ 220.282659] RBP: 00007f82683df4d0 R08: 00007f82683df5e0 R09: 00007f82683df4b0
[ 220.282663] R10: 00001d04000a0600 R11: 0000000000000246 R12: 00000000c0186444
[ 220.282667] R13: 0000000000000018 R14: 00007f82683df588 R15: 0000000000000003
[ 220.282689] </TASK>
[ 220.282693] irq event stamp: 6232311
[ 220.282697] hardirqs last enabled at (6232319): [<ffffffff9718cd7e>]
__up_console_sem+0x5e/0x70
[ 220.282704] hardirqs last disabled at (6232326):
[<ffffffff9718cd63>] __up_console_sem+0x43/0x70
[ 220.282709] softirqs last enabled at (6232072): [<ffffffff970ff669>]
__irq_exit_rcu+0xf9/0x170
[ 220.282716] softirqs last disabled at (6232061):
[<ffffffff970ff669>] __irq_exit_rcu+0xf9/0x170
[ 220.282722] ---[ end trace 0000000000000000 ]---

Full kernel log is here:
https://pastebin.com/gn01DVxE

My GPU hardware is AMD Radeon 6900XT.

Next message: Tony Lindgren: "Re: [PATCH v1 1/3] Revert "driver core: Delete driver_deferred_probe_check_state()""
Previous message: Melissa Wen: "Re: [BUG][5.20] refcount_t: underflow; use-after-free"
In reply to: Melissa Wen: "Re: [BUG][5.20] refcount_t: underflow; use-after-free"
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