CVE-2021-47131
net/tls: Fix use-after-free after the TLS device goes down and up
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
In the Linux kernel, the following vulnerability has been resolved:
net/tls: Fix use-after-free after the TLS device goes down and up
When a netdev with active TLS offload goes down, tls_device_down is
called to stop the offload and tear down the TLS context. However, the
socket stays alive, and it still points to the TLS context, which is now
deallocated. If a netdev goes up, while the connection is still active,
and the data flow resumes after a number of TCP retransmissions, it will
lead to a use-after-free of the TLS context.
This commit addresses this bug by keeping the context alive until its
normal destruction, and implements the necessary fallbacks, so that the
connection can resume in software (non-offloaded) kTLS mode.
On the TX side tls_sw_fallback is used to encrypt all packets. The RX
side already has all the necessary fallbacks, because receiving
non-decrypted packets is supported. The thing needed on the RX side is
to block resync requests, which are normally produced after receiving
non-decrypted packets.
The necessary synchronization is implemented for a graceful teardown:
first the fallbacks are deployed, then the driver resources are released
(it used to be possible to have a tls_dev_resync after tls_dev_del).
A new flag called TLS_RX_DEV_DEGRADED is added to indicate the fallback
mode. It's used to skip the RX resync logic completely, as it becomes
useless, and some objects may be released (for example, resync_async,
which is allocated and freed by the driver).
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net/tls: corrige el use-after-free después de que el dispositivo TLS se cae y se enciende. Cuando un netdev con descarga TLS activa se cae, se llama a tls_device_down para detener la descarga y derribarlo. el contexto TLS. Sin embargo, el socket permanece activo y todavía apunta al contexto TLS, que ahora está desasignado. Si se activa un netdev, mientras la conexión aún está activa, y el flujo de datos se reanuda después de varias retransmisiones TCP, se producirá un use-after-free del contexto TLS. Esta commit soluciona este error manteniendo vivo el contexto hasta su destrucción normal e implementa las alternativas necesarias para que la conexión pueda reanudarse en modo kTLS de software (no descargado). En el lado TX, tls_sw_fallback se utiliza para cifrar todos los paquetes. El lado RX ya tiene todos los respaldos necesarios, porque se admite la recepción de paquetes no descifrados. Lo que se necesita en el lado RX es bloquear las solicitudes de resincronización, que normalmente se producen después de recibir paquetes no descifrados. Se implementa la sincronización necesaria para un desmontaje elegante: primero se implementan los respaldos, luego se liberan los recursos del controlador (antes era posible tener un tls_dev_resync después de tls_dev_del). Se agrega una nueva bandera llamada TLS_RX_DEV_DEGRADED para indicar el modo de reserva. Se utiliza para omitir completamente la lógica de resincronización RX, ya que se vuelve inútil y algunos objetos pueden liberarse (por ejemplo, resync_async, que el controlador asigna y libera).
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-03-04 CVE Reserved
- 2024-03-15 CVE Published
- 2024-03-16 EPSS Updated
- 2024-12-19 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (4)
URL | Tag | Source |
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https://git.kernel.org/stable/c/e8f69799810c32dd40c6724d829eccc70baad07f | Vuln. Introduced |
URL | Date | SRC |
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URL | Date | SRC |
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Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
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Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 4.18 < 5.10.43 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.18 < 5.10.43" | en |
Affected
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Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 4.18 < 5.12.10 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.18 < 5.12.10" | en |
Affected
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Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 4.18 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.18 < 5.13" | en |
Affected
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