EUVD-2025-201641Lifecycle Timeline
4Description
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.
Analysis
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.
Technical Context
An out-of-bounds memory access occurs when code reads from or writes to memory locations outside the intended buffer boundaries.
Remediation
Implement proper bounds checking on all array and buffer accesses. Use memory-safe languages or static analysis tools to detect OOB issues.
Priority Score
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External POC / Exploit Code
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