CVE-2025-40304
fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds
Description
In the Linux kernel, the following vulnerability has been resolved: fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Add bounds checking to prevent writes past framebuffer boundaries when rendering text near screen edges. Return early if the Y position is off-screen and clip image height to screen boundary. Break from the rendering loop if the X position is off-screen. When clipping image width to fit the screen, update the character count to match the clipped width to prevent buffer size mismatches. Without the character count update, bit_putcs_aligned and bit_putcs_unaligned receive mismatched parameters where the buffer is allocated for the clipped width but cnt reflects the original larger count, causing out-of-bounds writes.
INFO
Published Date :
Dec. 8, 2025, 1:16 a.m.
Last Modified :
Dec. 8, 2025, 1:16 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Add bounds checking for Y position.
- Clip image height to screen boundary.
- Break loop if X position is off-screen.
- Update character count after clipping width.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-40304.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-40304 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-40304
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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CVE-2025-40304 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-40304 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Dec. 08, 2025
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Add bounds checking to prevent writes past framebuffer boundaries when rendering text near screen edges. Return early if the Y position is off-screen and clip image height to screen boundary. Break from the rendering loop if the X position is off-screen. When clipping image width to fit the screen, update the character count to match the clipped width to prevent buffer size mismatches. Without the character count update, bit_putcs_aligned and bit_putcs_unaligned receive mismatched parameters where the buffer is allocated for the clipped width but cnt reflects the original larger count, causing out-of-bounds writes. Added Reference https://git.kernel.org/stable/c/15ba9acafb0517f8359ca30002c189a68ddbb939 Added Reference https://git.kernel.org/stable/c/1943b69e87b0ab35032d47de0a7fca9a3d1d6fc1 Added Reference https://git.kernel.org/stable/c/2d1359e11674ed4274934eac8a71877ae5ae7bbb Added Reference https://git.kernel.org/stable/c/3637d34b35b287ab830e66048841ace404382b67 Added Reference https://git.kernel.org/stable/c/86df8ade88d290725554cefd03101ecd0fbd3752 Added Reference https://git.kernel.org/stable/c/996bfaa7372d6718b6d860bdf78f6618e850c702 Added Reference https://git.kernel.org/stable/c/ebc0730b490c7f27340b1222e01dd106e820320d Added Reference https://git.kernel.org/stable/c/f0982400648a3e00580253e0c48e991f34d2684c