CVE-2021-47563

ice: avoid bpf_prog refcount underflow

Severity Score

5.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

In the Linux kernel, the following vulnerability has been resolved:

ice: avoid bpf_prog refcount underflow

Ice driver has the routines for managing XDP resources that are shared
between ndo_bpf op and VSI rebuild flow. The latter takes place for
example when user changes queue count on an interface via ethtool's
set_channels().

There is an issue around the bpf_prog refcounting when VSI is being
rebuilt - since ice_prepare_xdp_rings() is called with vsi->xdp_prog as
an argument that is used later on by ice_vsi_assign_bpf_prog(), same
bpf_prog pointers are swapped with each other. Then it is also
interpreted as an 'old_prog' which in turn causes us to call
bpf_prog_put on it that will decrement its refcount.

Below splat can be interpreted in a way that due to zero refcount of a
bpf_prog it is wiped out from the system while kernel still tries to
refer to it:

[ 481.069429] BUG: unable to handle page fault for address: ffffc9000640f038
[ 481.077390] #PF: supervisor read access in kernel mode
[ 481.083335] #PF: error_code(0x0000) - not-present page
[ 481.089276] PGD 100000067 P4D 100000067 PUD 1001cb067 PMD 106d2b067 PTE 0
[ 481.097141] Oops: 0000 [#1] PREEMPT SMP PTI
[ 481.101980] CPU: 12 PID: 3339 Comm: sudo Tainted: G OE 5.15.0-rc5+ #1
[ 481.110840] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS GRRFCRB1.86B.0276.D07.1605190235 05/19/2016
[ 481.122021] RIP: 0010:dev_xdp_prog_id+0x25/0x40
[ 481.127265] Code: 80 00 00 00 00 0f 1f 44 00 00 89 f6 48 c1 e6 04 48 01 fe 48 8b 86 98 08 00 00 48 85 c0 74 13 48 8b 50 18 31 c0 48 85 d2 74 07 <48> 8b 42 38 8b 40 20 c3 48 8b 96 90 08 00 00 eb e8 66 2e 0f 1f 84
[ 481.148991] RSP: 0018:ffffc90007b63868 EFLAGS: 00010286
[ 481.155034] RAX: 0000000000000000 RBX: ffff889080824000 RCX: 0000000000000000
[ 481.163278] RDX: ffffc9000640f000 RSI: ffff889080824010 RDI: ffff889080824000
[ 481.171527] RBP: ffff888107af7d00 R08: 0000000000000000 R09: ffff88810db5f6e0
[ 481.179776] R10: 0000000000000000 R11: ffff8890885b9988 R12: ffff88810db5f4bc
[ 481.188026] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 481.196276] FS: 00007f5466d5bec0(0000) GS:ffff88903fb00000(0000) knlGS:0000000000000000
[ 481.205633] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 481.212279] CR2: ffffc9000640f038 CR3: 000000014429c006 CR4: 00000000003706e0
[ 481.220530] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 481.228771] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 481.237029] Call Trace:
[ 481.239856] rtnl_fill_ifinfo+0x768/0x12e0
[ 481.244602] rtnl_dump_ifinfo+0x525/0x650
[ 481.249246] ? __alloc_skb+0xa5/0x280
[ 481.253484] netlink_dump+0x168/0x3c0
[ 481.257725] netlink_recvmsg+0x21e/0x3e0
[ 481.262263] ____sys_recvmsg+0x87/0x170
[ 481.266707] ? __might_fault+0x20/0x30
[ 481.271046] ? _copy_from_user+0x66/0xa0
[ 481.275591] ? iovec_from_user+0xf6/0x1c0
[ 481.280226] ___sys_recvmsg+0x82/0x100
[ 481.284566] ? sock_sendmsg+0x5e/0x60
[ 481.288791] ? __sys_sendto+0xee/0x150
[ 481.293129] __sys_recvmsg+0x56/0xa0
[ 481.297267] do_syscall_64+0x3b/0xc0
[ 481.301395] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 481.307238] RIP: 0033:0x7f5466f39617
[ 481.311373] Code: 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb bd 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2f 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
[ 481.342944] RSP: 002b:00007ffedc7f4308 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
[ 481.361783] RAX: ffffffffffffffda RBX: 00007ffedc7f5460 RCX: 00007f5466f39617
[ 481.380278] RDX: 0000000000000000 RSI: 00007ffedc7f5360 RDI: 0000000000000003
[ 481.398500] RBP: 00007ffedc7f53f0 R08: 0000000000000000 R09: 000055d556f04d50
[ 481.416463] R10: 0000000000000077 R11: 0000000000000246 R12: 00007ffedc7f5360
[ 481.434131] R13: 00007ffedc7f5350 R14: 00007ffedc7f5344 R15: 0000000000000e98
[ 481.451520] Modules linked in: ice
---truncated---

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: ice: evitar el subdesbordamiento de refcount de bpf_prog El controlador Ice tiene rutinas para administrar los recursos XDP que se comparten entre la operación ndo_bpf y el flujo de reconstrucción VSI. Esto último ocurre, por ejemplo, cuando el usuario cambia el recuento de cola en una interfaz a través de set_channels() de ethtool. Hay un problema relacionado con el recuento de bpf_prog cuando se reconstruye VSI: dado que se llama a ice_prepare_xdp_rings() con vsi->xdp_prog como argumento que ice_vsi_assign_bpf_prog() usa más adelante, los mismos punteros de bpf_prog se intercambian entre sí. Luego también se interpreta como un 'old_prog' que a su vez hace que llamemos a bpf_prog_put, lo que disminuirá su recuento. El siguiente símbolo se puede interpretar de una manera que, debido al recuento cero de un bpf_prog, se elimina del sistema mientras el kernel todavía intenta hacer referencia a él: [481.069429] ERROR: no se puede manejar el error de página para la dirección: ffffc9000640f038 [481.077390] # PF: acceso de lectura de supervisor en modo kernel [ 481.083335] #PF: error_code(0x0000) - página no presente [ 481.089276] PGD 100000067 P4D 100000067 PUD 1001cb067 PMD 106d2b067 PTE 0 [ 481.097141] : 0000 [#1] ANTICIPACIÓN SMP PTI [ 481.101980] CPU: 12 PID: 3339 Comm: sudo Tainted: G OE 5.15.0-rc5+ #1 [ 481.110840] Nombre de hardware: Intel Corp. GRANTLEY/GRANTLEY, BIOS GRRFCRB1.86B.0276.D07.1605190235 19/05/2016 [ 481.122021] RIP: 0010:dev_xdp_prog_id+0x25/0x40 [ 481.127265] Código: 80 00 00 00 00 0f 1f 44 00 00 89 f6 48 c1 e6 04 48 01 fe 48 8b 86 98 08 00 00 48 85 c0 74 13 48 8b 50 18 31 c0 48 85 d2 74 07 <48> 8b 42 38 8b 40 20 c3 48 8b 96 90 08 00 00 eb e8 66 2e 0f 1f 84 [ 481.148991] RSP: ffffc90007b638 68 EFLAGS: 00010286 [481.155034] RAX: 0000000000000000 RBX: ffff889080824000 RCX: 0000000000000000 [ 481.163278] RDX: ffffc9000640f000 RSI: ffff889080824010 RDI: ffff889080824000 [ 481.171527] ffff888107af7d00 R08: 0000000000000000 R09: ffff88810db5f6e0 [ 481.179776] R10: 00000000000000000 R11: ffff8890885b9988 R12: ffff88810db5f4bc [ 481.188026] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 481.196276] FS: 00007f5466d5bec0(0000) GS:ffff88903fb00000(0000) knlGS:0000000000000000 [ 48 1.205633] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 481.212279] CR2: ffffc9000640f038 CR3: 000000014429c006 CR4: 00000000003706e0 [ 481.220530] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 481.228771] DR3: 00000000000000000 DR6: 00000000ffe0ff0 7: 0000000000000400 [481.237029] Seguimiento de llamadas: [481.239856] rtnl_fill_ifinfo+0x768/0x12e0 [481.244602] rtnl_dump_ifinfo+0x525/0x650 [481.249246] ? __alloc_skb+0xa5/0x280 [ 481.253484] netlink_dump+0x168/0x3c0 [ 481.257725] netlink_recvmsg+0x21e/0x3e0 [ 481.262263] ____sys_recvmsg+0x87/0x170 [ 481.2 66707] ? __might_fault+0x20/0x30 [ 481.271046] ? _copia_de_usuario+0x66/0xa0 [481.275591] ? iovec_from_user+0xf6/0x1c0 [ 481.280226] ___sys_recvmsg+0x82/0x100 [ 481.284566] ? sock_sendmsg+0x5e/0x60 [481.288791]? __sys_sendto+0xee/0x150 [ 481.293129] __sys_recvmsg+0x56/0xa0 [ 481.297267] do_syscall_64+0x3b/0xc0 [ 481.301395] Entry_SYSCALL_64_after_hwframe+0x44/0xae [ 481.307238] RIP: 0033:0x7f5466f39617 [ 481.311373] Código: 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb bd 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2f 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 2 8 89 54 24 1c 48 89 74 24 10 [ 481.342944] RSP: 002b:00007ffedc7f4308 EFLAGS: 00000246 ORIG_RAX: 0000000000000002f [ 481.361783] RAX: ffffffffffffffda RBX: 00007ffedc7f5460 RCX: 00007f5466f39617 [ 481.380278] RDX: 0000000000000000 RSI: 00007ffedc7f5360 RDI: 000000000000003 [ 481.398500] R PA : 00007ffedc7f53f0 R08: 0000000000000000 R09: 000055d556f04d50 [ 481.416463] R10: 0000000000000077 R11: 0000000000000246 R12: ffedc7f5360 [ 481.434131] R13: 00007ffedc7f5350 R14: 00007ffedc7f5344 R15: 0000000000000e98 [ 481.451520] Módulos vinculados en: ice ---truncado---

*Credits: N/A

CVSS Scores

CISAv3.1 5.5

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2024-05-24 CVE Reserved
2024-05-24 CVE Published
2024-05-25 EPSS Updated
2024-12-19 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (4)

URL	Tag	Source
https://git.kernel.org/stable/c/efc2214b6047b6f5b4ca53151eba62521b9452d6	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/e65a8707b4cd756d26d246bb2b9fab06eebafac1	2021-12-01
https://git.kernel.org/stable/c/1f10b09ccc832698ef4624a6ab9a213b6ccbda76	2021-12-01
https://git.kernel.org/stable/c/f65ee535df775a13a1046c0a0b2d72db342f8a5b	2021-11-22

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.5 < 5.10.83 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.5 < 5.10.83"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.5 < 5.15.6 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.5 < 5.15.6"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.5 < 5.16 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.5 < 5.16"		en		Affected