Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font() When fbcon_do_set_font() fails (e.g., due to a memory allocation failure inside vc_resize() under heavy memory pressure), it jumps to the `err_out` label to roll back the console state. However, the current rollback logic forgets to restore the `hi_font` state, leading to a severe state machine corruption. Earlier in the function, `set_vc_hi_font()` might be called to change `vc->vc_hi_font_mask` and mutate the screen buffer. If `vc_resize()` subsequently fails, the `err_out` path restores `vc_font.charcount` but entirely skips rolling back the `vc_hi_font_mask` and the screen buffer. This mismatch leaves the terminal in a desynchronized state. Because `vc_hi_font_mask` remains set, the VT subsystem will still accept character indices greater than 255 from userspace and write them to the screen buffer. Subsequent rendering calls (e.g., `fbcon_putcs()`) will then use these inflated indices to access the reverted, 256-character font array, leading to a deterministic out-of-bounds read and potential kernel memory disclosure. Fix this by adding the missing rollback logic for the `hi_font` mask and screen buffer in the error path.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 868749a7456dc48e93887a8474194e2ee6d6c21f before cb016bcb40c81e7b19c4ae6143babb366dae8e20; affected ebd6f886aa2447fcfcdce5450c9e1028e1d681bb before ac562193c36696513ae196171892e9338475c4bc; affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 before 3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5; affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 before a7a526fbc847f07ad3a503c7382189be5ab68574; affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 before b5bb2c696e140c399cb874def2feedf61dee27d6; affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 before 076b1aa65f77a49bce5a48a4a55a397cfcafa2b8; affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 before 39815715cbcfabb16fc8c5f4a23deeda20f5df62; affected a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 before 8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2; affected f08ccb792d3eaf1dc62d8cbf6a30d6522329f660; affected 5.10.249 before 5.10.261; affected 5.15.64 before 5.15.212; affected 5.19.6 before 5.20 |
| Linux / Linux | affected 6.0; unaffected 0 before 6.0; unaffected 5.10.261 through 5.10.*; unaffected 5.15.212 through 5.15.*; unaffected 6.1.178 through 6.1.*; unaffected 6.6.145 through 6.6.*; unaffected 6.12.96 through 6.12.*; unaffected 6.18.39 through 6.18.*; unaffected 7.1.3 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/cb016bcb40c81e7b19c4ae6143babb366dae8e20
- https://git.kernel.org/stable/c/ac562193c36696513ae196171892e9338475c4bc
- https://git.kernel.org/stable/c/3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5
- https://git.kernel.org/stable/c/a7a526fbc847f07ad3a503c7382189be5ab68574
- https://git.kernel.org/stable/c/b5bb2c696e140c399cb874def2feedf61dee27d6
- https://git.kernel.org/stable/c/076b1aa65f77a49bce5a48a4a55a397cfcafa2b8
- https://git.kernel.org/stable/c/39815715cbcfabb16fc8c5f4a23deeda20f5df62
- https://git.kernel.org/stable/c/8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2
ADP enrichment
No English description supplied.
No references supplied.