Linux Kernel up to 6.10.4 sc16is7xx kfifo_out_linear_ptr buffer overflow

Summaryinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.10.4. This impacts the function kfifo_out_linear_ptr of the component sc16is7xx. The manipulation leads to buffer overflow. This vulnerability is uniquely identified as CVE-2024-44951. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.10.4. This issue affects the function kfifo_out_linear_ptr of the component sc16is7xx. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: serial: sc16is7xx: fix TX fifo corruption Sometimes, when a packet is received on channel A at almost the same time as a packet is about to be transmitted on channel B, we observe with a logic analyzer that the received packet on channel A is transmitted on channel B. In other words, the Tx buffer data on channel B is corrupted with data from channel A. The problem appeared since commit 4409df5866b7 ("serial: sc16is7xx: change EFR lock to operate on each channels"), which changed the EFR locking to operate on each channel instead of chip-wise. This commit has introduced a regression, because the EFR lock is used not only to protect the EFR registers access, but also, in a very obscure and undocumented way, to protect access to the data buffer, which is shared by the Tx and Rx handlers, but also by each channel of the IC. Fix this regression first by switching to kfifo_out_linear_ptr() in sc16is7xx_handle_tx() to eliminate the need for a shared Rx/Tx buffer. Secondly, replace the chip-wise Rx buffer with a separate Rx buffer for each channel.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2024-44951 since 08/21/2024. The exploitation is known to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/10/2024).

The vulnerability scanner Nessus provides a plugin with the ID 208423 (SUSE SLES15 / openSUSE 15 Security Update : kernel (SUSE-SU-2024:3551-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.10.5 eliminates this vulnerability. Applying the patch 09cfe05e9907/133f4c00b8b2 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (208423). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.10.0
• 6.10.1
• 6.10.2
• 6.10.3
• 6.10.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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