CVE-2021-46935

Description

In the Linux kernel, the following vulnerability has been resolved: binder: fix async_free_space accounting for empty parcels In 4.13, commit 74310e06be4d ("android: binder: Move buffer out of area shared with user space") fixed a kernel structure visibility issue. As part of that patch, sizeof(void *) was used as the buffer size for 0-length data payloads so the driver could detect abusive clients sending 0-length asynchronous transactions to a server by enforcing limits on async_free_size. Unfortunately, on the "free" side, the accounting of async_free_space did not add the sizeof(void *) back. The result was that up to 8-bytes of async_free_space were leaked on every async transaction of 8-bytes or less. These small transactions are uncommon, so this accounting issue has gone undetected for several years. The fix is to use "buffer_size" (the allocated buffer size) instead of "size" (the logical buffer size) when updating the async_free_space during the free operation. These are the same except for this corner case of asynchronous transactions with payloads < 8 bytes.

Gravité et risque d'exploitation

CVE-2021-46935 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.23 %, ce qui la place devant 12.9 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <cfd0d84ba28c18b531648c9d4a35ecca89ad9901, <7c7064402609aeb6fb11be1b4ec10673ff17b593, 5.16, 5.15.13, 0, 74310e06be4d74dcf67cd108366710dee5c576d5, <17691bada6b2f1d5f1c0f6d28cd9d0727023b0ff, <=5.10.*, <=4.14.*, 4.19.224, <=5.4.*, 5.4.170, <=4.19.*, <1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4, 5.10.90, <=*, <4.14, <=5.15.*, 4.14.261, <2d2df539d05205fd83c404d5f2dff48d36f9b495, <103b16a8c51f96d5fe063022869ea906c256e5da, 4.14) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/2d2df539d05205fd83c404d5f2dff48d36f9b495
• https://git.kernel.org/stable/c/7c7064402609aeb6fb11be1b4ec10673ff17b593
• https://git.kernel.org/stable/c/103b16a8c51f96d5fe063022869ea906c256e5da
• https://git.kernel.org/stable/c/1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4
• https://git.kernel.org/stable/c/17691bada6b2f1d5f1c0f6d28cd9d0727023b0ff
• https://git.kernel.org/stable/c/cfd0d84ba28c18b531648c9d4a35ecca89ad9901