CVE-2021-46947

sfc: adjust efx->xdp_tx_queue_count with the real number of initialized queues

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:

sfc: adjust efx->xdp_tx_queue_count with the real number of initialized queues

efx->xdp_tx_queue_count is initially initialized to num_possible_cpus() and is
later used to allocate and traverse efx->xdp_tx_queues lookup array. However,
we may end up not initializing all the array slots with real queues during
probing. This results, for example, in a NULL pointer dereference, when running
"# ethtool -S <iface>", similar to below

[2570283.664955][T4126959] BUG: kernel NULL pointer dereference, address: 00000000000000f8
[2570283.681283][T4126959] #PF: supervisor read access in kernel mode
[2570283.695678][T4126959] #PF: error_code(0x0000) - not-present page
[2570283.710013][T4126959] PGD 0 P4D 0
[2570283.721649][T4126959] Oops: 0000 [#1] SMP PTI
[2570283.734108][T4126959] CPU: 23 PID: 4126959 Comm: ethtool Tainted: G O 5.10.20-cloudflare-2021.3.1 #1
[2570283.752641][T4126959] Hardware name: <redacted>
[2570283.781408][T4126959] RIP: 0010:efx_ethtool_get_stats+0x2ca/0x330 [sfc]
[2570283.796073][T4126959] Code: 00 85 c0 74 39 48 8b 95 a8 0f 00 00 48 85 d2 74 2d 31 c0 eb 07 48 8b 95 a8 0f 00 00 48 63 c8 49 83 c4 08 83 c0 01 48 8b 14 ca <48> 8b 92 f8 00 00 00 49 89 54 24 f8 39 85 a0 0f 00 00 77 d7 48 8b
[2570283.831259][T4126959] RSP: 0018:ffffb79a77657ce8 EFLAGS: 00010202
[2570283.845121][T4126959] RAX: 0000000000000019 RBX: ffffb799cd0c9280 RCX: 0000000000000018
[2570283.860872][T4126959] RDX: 0000000000000000 RSI: ffff96dd970ce000 RDI: 0000000000000005
[2570283.876525][T4126959] RBP: ffff96dd86f0a000 R08: ffff96dd970ce480 R09: 000000000000005f
[2570283.892014][T4126959] R10: ffffb799cd0c9fff R11: ffffb799cd0c9000 R12: ffffb799cd0c94f8
[2570283.907406][T4126959] R13: ffffffffc11b1090 R14: ffff96dd970ce000 R15: ffffffffc11cd66c
[2570283.922705][T4126959] FS: 00007fa7723f8740(0000) GS:ffff96f51fac0000(0000) knlGS:0000000000000000
[2570283.938848][T4126959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[2570283.952524][T4126959] CR2: 00000000000000f8 CR3: 0000001a73e6e006 CR4: 00000000007706e0
[2570283.967529][T4126959] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[2570283.982400][T4126959] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[2570283.997308][T4126959] PKRU: 55555554
[2570284.007649][T4126959] Call Trace:
[2570284.017598][T4126959] dev_ethtool+0x1832/0x2830

Fix this by adjusting efx->xdp_tx_queue_count after probing to reflect the true
value of initialized slots in efx->xdp_tx_queues.

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: sfc: ajuste efx->xdp_tx_queue_count con el número real de colas inicializadas. efx->xdp_tx_queue_count se inicializa inicialmente en num_possible_cpus() y luego se usa para asignar y recorrer la búsqueda de efx->xdp_tx_queues formación. Sin embargo, es posible que terminemos sin inicializar todas las ranuras de la matriz con colas reales durante el sondeo. Esto da como resultado, por ejemplo, una desreferencia del puntero NULL, cuando se ejecuta "# ethtool -S ", similar a lo siguiente [2570283.664955][T4126959] ERROR: desreferencia del puntero NULL del kernel, dirección: 000000000000000f8 [2570283.681283][T4126959] # PF: acceso de lectura de supervisor en modo kernel [2570283.695678][T4126959] #PF: error_code(0x0000) - página no presente [2570283.710013][T4126959] PGD 0 P4D 0 [2570283.721649][T4126959] Ups: 0000 [# 1]MPD PTI [2570283.734108][T4126959] CPU: 23 PID: 4126959 Comunicaciones: ethtool Contaminado: GO 5.10.20-cloudflare-2021.3.1 #1 [2570283.752641][T4126959] Nombre de hardware: [2570283.78140 8][T4126959] QEPD: 0010:efx_ethtool_get_stats+0x2ca/0x330 [sfc] [2570283.796073][T4126959] Código: 00 85 c0 74 39 48 8b 95 a8 0f 00 00 48 85 d2 74 2d 31 c0 eb 07 48 8b 95 a8 0f 00 00 48 63 c8 49 83 c4 08 83 c0 01 48 8b 14 ca <48> 8b 92 f8 00 00 00 49 89 54 24 f8 39 85 a0 0f 00 00 77 d7 48 8b [2570283.831259][T4126959] RSP: 0018:ff ffb79a77657ce8 EFLAGS: 00010202 [2570283.845121 ][T4126959] RAX: 0000000000000019 RBX: ffffb799cd0c9280 RCX: 0000000000000018 [2570283.860872][T4126959] RDX: 0000000000000000 RSI: ffff96dd 970ce000 RDI: 0000000000000005 [2570283.876525][T4126959] RBP: ffff96dd86f0a000 R08: ffff96dd970ce480 R09: 000000000000005f [2570283.892014][T4 126959]R10 : ffffb799cd0c9fff R11: ffffb799cd0c9000 R12: ffffb799cd0c94f8 [2570283.907406][T4126959] R13: ffffffffc11b1090 R14: ffff96dd970ce000 R15: ffffffffc11cd66 c [2570283.922705][T4126959] FS: 00007fa7723f8740(0000) GS:ffff96f51fac0000(0000) knlGS:00000000000000000 [2570283.938848][T4126959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [2570283.952524][T4126959] CR2: 000000000000000f8 CR3: 0000001a73e6e006 CR4: 00000000007706 e0 [2570283.967529][T4126959] DR0: 00000000000000000 DR1: 0000000000000000 DR2: 00000000000000000 [2570283.982400][T4126959] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [2570283.997308][T4126959] PKRU: 55555554 [2570284.007649][T4126959] Seguimiento de llamadas: [257 0284.017598][T4126959] dev_ethtool+0x1832/0x2830 Solucione este problema ajustando efx->xdp_tx_queue_count después de sondear para reflejar el verdadero valor de las ranuras inicializadas en efx->xdp_tx_queues.

*Credits: N/A

CVSS Scores

NISTv3.1 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

2024-02-25 CVE Reserved
2024-02-27 CVE Published
2024-02-28 EPSS Updated
2024-08-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-476: NULL Pointer Dereference

CAPEC

References (3)

URL	Tag	Source
https://git.kernel.org/stable/c/e26ca4b535820b1445dcef3c0f82b3fb5b45108b	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/ebeac958b690123a0b40aa61f688f2f170035fad	2021-05-12
https://git.kernel.org/stable/c/99ba0ea616aabdc8e26259fd722503e012199a76	2021-04-27

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"				>= 5.12 < 5.12.3 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.12.3"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 5.12 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12 < 5.13"		en		Affected