CVE-2026-53402

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()<br /> <br /> When fbcon_do_set_font() fails (e.g., due to a memory allocation failure<br /> inside vc_resize() under heavy memory pressure), it jumps to the `err_out`<br /> label to roll back the console state. However, the current rollback logic<br /> forgets to restore the `hi_font` state, leading to a severe state machine<br /> corruption.<br /> <br /> Earlier in the function, `set_vc_hi_font()` might be called to change<br /> `vc-&gt;vc_hi_font_mask` and mutate the screen buffer. If `vc_resize()`<br /> subsequently fails, the `err_out` path restores `vc_font.charcount`<br /> but entirely skips rolling back the `vc_hi_font_mask` and the screen<br /> buffer.<br /> <br /> This mismatch leaves the terminal in a desynchronized state. Because<br /> `vc_hi_font_mask` remains set, the VT subsystem will still accept<br /> character indices greater than 255 from userspace and write them to the<br /> screen buffer. Subsequent rendering calls (e.g., `fbcon_putcs()`) will<br /> then use these inflated indices to access the reverted, 256-character<br /> font array, leading to a deterministic out-of-bounds read and potential<br /> kernel memory disclosure.<br /> <br /> Fix this by adding the missing rollback logic for the `hi_font` mask<br /> and screen buffer in the error path.