7.1 HIGH
- CVSS version (CVSS): 3.1
- Attack Vector (AV): Local (L)
- Attack Complexity (AC): Low (L)
- Privileges Required (PR): Low (L)
- User Interaction (UI): None (N)
- Scope (S): Unchanged (U)
- Confidentiality (C): High (H)
- Integrity (I): None (N)
- Availability (A): High (H)
- Modified Attack Vector (MAV): Local (L)
- Modified Attack Complexity (MAC): Low (L)
- Modified Privileges Required (MPR): Low (L)
- Modified User Interaction (MUI): None (N)
- Modified Confidentiality (MC): High (H)
- Modified Scope (MS): Unchanged (U)
- Modified Integrity (MI): None (N)
- Modified Availability (MA): High (H)
Activity log
- Created & dismissed (max. allowed matches exceeded) suggestion
fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()
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.
References
Affected products
- <076b1aa65f77a49bce5a48a4a55a397cfcafa2b8
- ==f08ccb792d3eaf1dc62d8cbf6a30d6522329f660
- <5.16
- ==ebd6f886aa2447fcfcdce5450c9e1028e1d681bb
- <6.0
- <39815715cbcfabb16fc8c5f4a23deeda20f5df62
- =<6.18.*
- <5.11
- <8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2
- =<6.12.*
- =<7.1.*
- ==6.0
- <5.20
- =<*
- ==868749a7456dc48e93887a8474194e2ee6d6c21f
- <b5bb2c696e140c399cb874def2feedf61dee27d6