Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: fbdev: core: Fix pointer desynchronization in fb_io_read() In fb_io_read(), if copy_to_user() performs a partial copy (e.g., due to a faulty user buffer), the loop adjusts the chunk size 'c' and updates the remaining 'count'. However, the hardware 'src' pointer has already been eagerly advanced by the original chunk size. If the loop is allowed to continue, the read will resume from an incorrect, over-advanced offset. Since the remaining 'count' was only decremented by the successful bytes, this desynchronization causes the next iterations to execute more hardware reads than originally bounded, eventually leading to out-of-bounds I/O reads. Fix this by breaking out of the loop immediately upon a partial copy_to_user(). A partial copy indicates a faulty user buffer, making subsequent read attempts futile. Breaking out ensures we return the number of successfully read bytes without risking out-of-bounds hardware accesses in subsequent mismatched iterations.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff before 42bc07b4e5a3c8a02a433388f562a8f46d093e11; affected 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff before 42a6d8126c194133eafab2b0fd5c8668ebfcba5b; affected 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff before 7ff87a01ae3a8cd0208f7499386998223a8b5dba; affected 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff before 7110b7b794a2aac2c5cf8eb06ebf2af724c74d50; affected 6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff before 81cc73be40c6f028f1ee3f438ace46afe666dbae |
| Linux / Linux | affected 6.5; unaffected 0 before 6.5; unaffected 6.6.153 through 6.6.*; unaffected 6.12.105 through 6.12.*; unaffected 6.18.46 through 6.18.*; unaffected 7.1.10 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/42bc07b4e5a3c8a02a433388f562a8f46d093e11
- https://git.kernel.org/stable/c/42a6d8126c194133eafab2b0fd5c8668ebfcba5b
- https://git.kernel.org/stable/c/7ff87a01ae3a8cd0208f7499386998223a8b5dba
- https://git.kernel.org/stable/c/7110b7b794a2aac2c5cf8eb06ebf2af724c74d50
- https://git.kernel.org/stable/c/81cc73be40c6f028f1ee3f438ace46afe666dbae
ADP enrichment
No English description supplied.
No references supplied.