Linux Kernel up to 5.14.9 tty vc_resize out-of-bounds

Summaryinfo

A vulnerability was found in Linux Kernel up to 5.14.9. It has been classified as problematic. Affected is the function vc_resize of the component tty. Performing a manipulation results in out-of-bounds. This vulnerability was named CVE-2021-47383. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 5.14.9. This affects the function vc_resize of the component tty. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: tty: Fix out-of-bound vmalloc access in imageblit This issue happens when a userspace program does an ioctl FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct containing only the fields xres, yres, and bits_per_pixel with values. If this struct is the same as the previous ioctl, the vc_resize() detects it and doesn't call the resize_screen(), leaving the fb_var_screeninfo incomplete. And this leads to the updatescrollmode() calculates a wrong value to fbcon_display->vrows, which makes the real_y() return a wrong value of y, and that value, eventually, causes the imageblit to access an out-of-bound address value. To solve this issue I made the resize_screen() be called even if the screen does not need any resizing, so it will "fix and fill" the fb_var_screeninfo independently.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2021-47383 since 05/21/2024. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 207773 (Oracle Linux 8 : kernel (ELSA-2024-7000)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.4.286, 4.9.285, 4.14.249, 4.19.209, 5.4.151, 5.10.71 or 5.14.10 eliminates this vulnerability. Applying the patch 7e71fcedfda6/70aed03b1d5a/067c694d0604/8a6a240f52e1/883f7897a25e/d570c48dd37d/699d926585da/3b0c40612471 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 (207773). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.4.285
• 4.9.284
• 4.14.248
• 4.19.208
• 5.4.150
• 5.10.0
• 5.10.1
• 5.10.2
• 5.10.3
• 5.10.4
• 5.10.5
• 5.10.6
• 5.10.7
• 5.10.8
• 5.10.9
• 5.10.10
• 5.10.11
• 5.10.12
• 5.10.13
• 5.10.14
• 5.10.15
• 5.10.16
• 5.10.17
• 5.10.18
• 5.10.19
• 5.10.20
• 5.10.21
• 5.10.22
• 5.10.23
• 5.10.24
• 5.10.25
• 5.10.26
• 5.10.27
• 5.10.28
• 5.10.29
• 5.10.30
• 5.10.31
• 5.10.32
• 5.10.33
• 5.10.34
• 5.10.35
• 5.10.36
• 5.10.37
• 5.10.38
• 5.10.39
• 5.10.40
• 5.10.41
• 5.10.42
• 5.10.43
• 5.10.44
• 5.10.45
• 5.10.46
• 5.10.47
• 5.10.48
• 5.10.49
• 5.10.50
• 5.10.51
• 5.10.52
• 5.10.53
• 5.10.54
• 5.10.55
• 5.10.56
• 5.10.57
• 5.10.58
• 5.10.59
• 5.10.60
• 5.10.61
• 5.10.62
• 5.10.63
• 5.10.64
• 5.10.65
• 5.10.66
• 5.10.67
• 5.10.68
• 5.10.69
• 5.10.70
• 5.14.0
• 5.14.1
• 5.14.2
• 5.14.3
• 5.14.4
• 5.14.5
• 5.14.6
• 5.14.7
• 5.14.8
• 5.14.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

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Countermeasuresinfo

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Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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