Re: [PATCH 0/1] misc/vmw_vmci: fix filling of the msg and msg_payload in dg_info struct

From: kovalev
Date: Wed Jan 10 2024 - 06:52:46 EST

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In reply to: Greg KH: "Re: [PATCH 0/1] misc/vmw_vmci: fix filling of the msg and msg_payload in dg_info struct"
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10.01.2024 13:53, Greg KH wrote:

On Wed, Jan 10, 2024 at 01:40:41PM +0300, kovalev@xxxxxxxxxxxx wrote:

Warning detected by tracking mechanisms __fortify_memcpy_chk, added 2021-04-20.
The proposed patch (PATCH 1/1) introduces changes to meet the new requirements.

The reproducer (repro.c) was generated using the syzkaller program and minimized
(Thanks Alexander Ofitserov <oficerovas@xxxxxxxxxxxx>):

#define _GNU_SOURCE

#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

uint64_t r[1] = {0xffffffffffffffff};

int main(void)
{
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
memset((void *)0x20000000ul, 0x0, 0x1000000ul);

intptr_t res = 0;
res = syscall(__NR_socket, 0x28ul, 2ul, 0);
if (res != -1)
r[0] = res;
*(uint16_t*)0x20000000 = 0x28;
*(uint16_t*)0x20000002 = 0;
*(uint32_t*)0x20000004 = 1;
*(uint32_t*)0x20000008 = 2;
*(uint32_t*)0x2000000c = 0;
syscall(__NR_connect, r[0], 0x20000000ul, 0x10ul);

// struct msghdr*
// 0x20000440ul - 0x20000447ul - msg_name
// 0x20000448ul - 0x20000449ul - msg_len
// 0x20000450ul - ptr to msg_iov
// 0x20000458ul - msg_iovlen
*(uint64_t*)0x20000450 = 0x20000400;
*(uint8_t*)0x20000448 = 0xFF;
*(uint64_t*)0x20000458 = 1;
*(uint64_t*)0x20000460 = 0x20010000;
*(uint64_t*)0x20000468 = 0;

// 0x20000400 - ptr to iov_base
// 0x20000408 - iov_len
*(uint64_t*)0x20000400 = 0x20000900;
strcpy((char *)0x20000900, "AAAAAA");
*(uint64_t*)0x20000408 = 0x10000;

syscall(__NR_sendmsg, r[0], 0x20000440ul, 0ul);
return 0;
}

$ gcc repro.c -o repro
$ ./repro

# dmesg (linux kernel 6.6.6):
-----
[ 38.036309] Guest personality initialized and is inactive
[ 38.036380] VMCI host device registered (name=vmci, major=10, minor=122)
[ 38.036381] Initialized host personality
[ 38.037987] NET: Registered PF_VSOCK protocol family
[ 38.073027] ------------[ cut here ]------------
[ 38.073034] memcpy: detected field-spanning write (size 65560) of single field "&dg_info->msg" at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)
[ 38.073103] WARNING: CPU: 9 PID: 3976 at drivers/misc/vmw_vmci/vmci_datagram.c:237 vmci_datagram_dispatch+0x378/0x3c0 [vmw_vmci]
[ 38.073135] Modules linked in: vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vsock vmw_vmci ccm rfcomm cmac algif_hash algif_skcipher af_alg af_packet qrtr bnep uvcvideo btusb uvc btrtl videobuf2_vmalloc videobuf2_memops btintel videobuf2_v4l2 btbcm btmtk usbhid videodev bluetooth videobuf2_common mc ecdh_generic joydev snd_sof_pci_intel_tgl snd_sof_intel_hda_common soundwire_intel soundwire_generic_allocation coretemp snd_sof_intel_hda_mlink intel_uncore_frequency soundwire_cadence intel_uncore_frequency_common intel_tcc_cooling snd_sof_intel_hda snd_sof_pci x86_pkg_temp_thermal snd_sof_xtensa_dsp intel_powerclamp snd_sof snd_sof_utils snd_soc_hdac_hda kvm_intel snd_hda_ext_core snd_soc_acpi_intel_match snd_soc_acpi snd_hda_codec_hdmi soundwire_bus snd_soc_core kvm hid_multitouch nls_utf8 snd_hda_codec_realtek hid_generic snd_compress nls_cp866 ac97_bus iwlmvm spi_pxa2xx_platform 8250_dw iTCO_wdt snd_pcm_dmaengine irqbypass dw_dmac snd_hda_codec_generic vfat rtsx_pci_sdmmc intel_pmc_bxt
[ 38.073247] crct10dif_pclmul fat ledtrig_audio snd_hda_intel crc32_pclmul mei_hdcp iTCO_vendor_support mmc_core intel_rapl_msr crc32c_intel snd_intel_dspcfg mac80211 ghash_clmulni_intel snd_intel_sdw_acpi sha512_ssse3 sha256_ssse3 snd_hda_codec sha1_ssse3 aesni_intel processor_thermal_device_pci processor_thermal_device snd_hda_core crypto_simd processor_thermal_rfim intel_lpss_pci i2c_hid_acpi ucsi_acpi cryptd libarc4 iwlwifi pcspkr xhci_pci processor_thermal_mbox intel_lpss ideapad_laptop i2c_hid xhci_pci_renesas i2c_i801 mei_me typec_ucsi snd_hwdep idma64 processor_thermal_rapl typec sparse_keymap wmi_bmof tiny_power_button cfg80211 snd_pcm i2c_smbus platform_profile rtsx_pci xhci_hcd mei virt_dma intel_rapl_common thermal hid roles fan button int3403_thermal battery rfkill int340x_thermal_zone int3400_thermal acpi_thermal_rel intel_pmc_core pinctrl_tigerlake acpi_pad ac sch_fq_codel vboxvideo drm_vram_helper drm_ttm_helper vboxsf vboxguest snd_seq_midi snd_seq_midi_event snd_seq snd_rawmidi snd_seq_device
[ 38.073342] snd_timer snd soundcore msr fuse dm_mod efi_pstore efivarfs ip_tables x_tables autofs4 i915 hwmon i2c_algo_bit drm_buddy ttm evdev drm_display_helper input_leds serio_raw cec rc_core intel_gtt video wmi
[ 38.073375] CPU: 9 PID: 3976 Comm: eee.out Not tainted 6.6.6-un-def-alt1 #1
[ 38.073381] Hardware name: LENOVO 82X8/LNVNB161216, BIOS LTCN30WW 11/08/2023
[ 38.073384] RIP: 0010:vmci_datagram_dispatch+0x378/0x3c0 [vmw_vmci]
[ 38.073405] Code: 38 fd ff ff 80 3d 5c 96 00 00 00 75 87 48 c7 c2 58 0b 6b c1 4c 89 ee 48 c7 c7 a0 0b 6b c1 c6 05 42 96 00 00 01 e8 18 c0 a1 c5 <0f> 0b e9 63 ff ff ff e8 1c 5e 65 c6 83 cd ff e9 fe fc ff ff f0 ff
[ 38.073410] RSP: 0018:ffffc9000279fb58 EFLAGS: 00010246
[ 38.073415] RAX: 0000000000000000 RBX: ffff88811a9c0000 RCX: 0000000000000000
[ 38.073418] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[ 38.073421] RBP: ffff888165540000 R08: 0000000000000000 R09: 0000000000000000
[ 38.073423] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888165540030
[ 38.073425] R13: 0000000000010018 R14: ffff8881090a2a00 R15: ffff88811a9c0018
[ 38.073428] FS: 00007f3a36bec580(0000) GS:ffff8882a7a40000(0000) knlGS:0000000000000000
[ 38.073432] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 38.073435] CR2: 000055b6120cf008 CR3: 000000010db62000 CR4: 0000000000750ee0
[ 38.073438] PKRU: 55555554
[ 38.073440] Call Trace:
[ 38.073446] <TASK>
[ 38.073448] ? vmci_datagram_dispatch+0x378/0x3c0 [vmw_vmci]
[ 38.073467] ? __warn+0x7d/0x130
[ 38.073482] ? vmci_datagram_dispatch+0x378/0x3c0 [vmw_vmci]
[ 38.073503] ? report_bug+0x17e/0x1b0
[ 38.073514] ? handle_bug+0x60/0xb0
[ 38.073523] ? exc_invalid_op+0x13/0x70
[ 38.073531] ? asm_exc_invalid_op+0x16/0x20
[ 38.073540] ? vmci_datagram_dispatch+0x378/0x3c0 [vmw_vmci]
[ 38.073559] ? vmci_datagram_dispatch+0x378/0x3c0 [vmw_vmci]
[ 38.073577] vmci_transport_dgram_enqueue+0xb5/0x150 [vmw_vsock_vmci_transport]
[ 38.073596] vsock_dgram_sendmsg+0xcf/0x180 [vsock]
[ 38.073618] ____sys_sendmsg+0x376/0x3b0
[ 38.073629] ? copy_msghdr_from_user+0x6d/0xb0
[ 38.073635] ___sys_sendmsg+0x86/0xe0
[ 38.073642] ? filemap_map_pages+0x423/0x570
[ 38.073653] ? vmci_resource_add+0xde/0x170 [vmw_vmci]
[ 38.073674] ? __pfx_vmci_transport_recv_dgram_cb+0x10/0x10 [vmw_vsock_vmci_transport]
[ 38.073689] ? do_fault+0x296/0x470
[ 38.073697] __sys_sendmsg+0x57/0xb0
[ 38.073704] do_syscall_64+0x59/0x90
[ 38.073711] ? count_memcg_events.constprop.0+0x3a/0x70
[ 38.073717] ? handle_mm_fault+0x9e/0x300
[ 38.073724] ? do_user_addr_fault+0x33d/0x680
[ 38.073733] ? sched_clock+0xc/0x30
[ 38.073740] ? get_vtime_delta+0xf/0xc0
[ 38.073750] ? ct_kernel_exit.isra.0+0x71/0x90
[ 38.073759] ? __ct_user_enter+0x5a/0xd0
[ 38.073765] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 38.073771] RIP: 0033:0x7f3a36b0cd49
[ 38.073776] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ef 70 0d 00 f7 d8 64 89 01 48
[ 38.073780] RSP: 002b:00007ffea38c4a08 EFLAGS: 00000217 ORIG_RAX: 000000000000002e
[ 38.073784] RAX: ffffffffffffffda RBX: 000055b6120ce2d0 RCX: 00007f3a36b0cd49
[ 38.073787] RDX: 0000000000000000 RSI: 0000000020000440 RDI: 0000000000000003
[ 38.073790] RBP: 00007ffea38c4a20 R08: 00007ffea38c4b10 R09: 00007ffea38c4b10
[ 38.073792] R10: 00007ffea38c4b10 R11: 0000000000000217 R12: 000055b6120ce060
[ 38.073795] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 38.073799] </TASK>
[ 38.073801] ---[ end trace 0000000000000000 ]---
-----

To assess the performance losses when using a new patch, the kernel was builded with the
patch below and the reproducer was launched several times:

diff --git a/drivers/misc/vmw_vmci/vmci_datagram.c b/drivers/misc/vmw_vmci/vmci_datagram.c
index 6d42f3b99c6f46..b078364d5c9b23 100644
--- a/drivers/misc/vmw_vmci/vmci_datagram.c
+++ b/drivers/misc/vmw_vmci/vmci_datagram.c
@@ -234,6 +234,17 @@ static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
dg_info->in_dg_host_queue = true;
dg_info->entry = dst_entry;
+ u32 i;
+ printk("memcpy: init i=%d\n",i);
+ for(i=0; i<1000000000;i++){
+ memcpy(&dg_info->msg, dg, 24);
+ }
+ printk("memcpy: old i=%d\n",i);
+ for(i=0; i<1000000000;i++){
+ memcpy(&dg_info->msg, dg, 12);
+ memcpy(dg_info->msg_payload, VMCI_DG_PAYLOAD(dg), 12);
+ }
+ printk("memcpy: new i=%d\n",i);
memcpy(&dg_info->msg, dg, VMCI_DG_HEADERSIZE);
if (dg->payload_size) {
memcpy(dg_info->msg_payload, VMCI_DG_PAYLOAD(dg), dg->payload_size);

=======
Reproducing
=======
# dmesg -w
----
[ 181.415379] Guest personality initialized and is inactive
[ 181.415659] VMCI host device registered (name=vmci, major=10, minor=122)
[ 181.415665] Initialized host personality
[ 181.422766] NET: Registered PF_VSOCK protocol family
[ 181.468022] memcpy: init i=0
[ 183.020694] memcpy: old i=1000000000
[ 184.572458] memcpy: new i=1000000000
[ 196.009873] memcpy: init i=0
[ 197.562651] memcpy: old i=1000000000
[ 199.118132] memcpy: new i=1000000000
[ 206.543691] memcpy: init i=0
[ 208.781697] memcpy: old i=1000000000
[ 211.020229] memcpy: new i=1000000000
----

$ node
Welcome to Node.js v16.19.1.
Type ".help" for more information.

183.020694 - 181.468022 //old

1.5526720000000012

184.572458 - 183.020694 // new

1.55176400000002

197.562651 - 196.009873 // old

1.5527779999999893

199.118132 - 197.562651 // new

1.5554810000000145

208.781697 - 206.543691 // old

2.238006000000013

211.020229 - 208.781697 // new

2.238531999999992
Based on a rather primitive performance assessment, the results do not differ
much, and given the loss of warning output in a one-time function call, the
difference will be significant.

[PATCH 1/1] misc/vmw_vmci: fix filling of the msg and msg_payload in dg_info struct

How is this different from the previously submitted patch series fo this
issue:
https://lore.kernel.org/r/20240105164001.2129796-1-harshit.m.mogalapalli@xxxxxxxxxx

The patch I propose fixes the occurrence of warnings in 2 places in the code, one place was detected by the syzkaller program, the second is potentially possible, since the method of filling in the structure is exactly the same.

I already sent this patch on 12/27/2023 to maintainers (bryantan@xxxxxxxxxx , vdasa@xxxxxxxxxx , pv-drivers@xxxxxxxxxx ,arnd@xxxxxxxx ), but due to the lack of a response from them, I decided to send it again, expanding the list of recipients.

--
Regards,
Vasiliy Kovalev

Next message: Breno Leitao: "Re: [PATCH net-next 10/10] net: fill in MODULE_DESCRIPTION()s for PCS Layer"
Previous message: Valentin Schneider: "[PATCH] sched/isolation: Warn about missing isolcpus mask"
In reply to: Greg KH: "Re: [PATCH 0/1] misc/vmw_vmci: fix filling of the msg and msg_payload in dg_info struct"
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