fbdev: core: Fix pointer desynchronization in fb_io_read()
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.
CVE-2026-80578
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-80578
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff",
"lessThan": "42bc07b4e5a3c8a02a433388f562a8f46d093e11",
"versionType": "git"
},
{
"status": "affected",
"version": "6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff",
"lessThan": "42a6d8126c194133eafab2b0fd5c8668ebfcba5b",
"versionType": "git"
},
{
"status": "affected",
"version": "6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff",
"lessThan": "7ff87a01ae3a8cd0208f7499386998223a8b5dba",
"versionType": "git"
},
{
"status": "affected",
"version": "6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff",
"lessThan": "7110b7b794a2aac2c5cf8eb06ebf2af724c74d50",
"versionType": "git"
},
{
"status": "affected",
"version": "6121cd9ef911432b14c2a17aefaf8cd2f3cfcdff",
"lessThan": "81cc73be40c6f028f1ee3f438ace46afe666dbae",
"versionType": "git"
}
],
"programFiles": [
"drivers/video/fbdev/core/fb_io_fops.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.5"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.5",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.153",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.105",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/video/fbdev/core/fb_io_fops.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-80578
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #34331 · Revision 1
- Added to Heist Feed
- Publisher date