xen/pvcalls: bound backend response req_id before indexing rsp[]
In the Linux kernel, the following vulnerability has been resolved: xen/pvcalls: bound backend response req_id before indexing rsp[] pvcalls_front_event_handler() takes req_id directly from the backend-supplied ring response and uses it to index the fixed-size bedata->rsp[] array for a memcpy() and a store, with no range check. A malicious or buggy backend can set req_id past PVCALLS_NR_RSP_PER_RING and drive an out-of-bounds write past the bedata allocation. req_id was also declared int while the wire field rsp->req_id is u32, so a range check on the signed value alone is insufficient: a backend req_id of 0xffffffff becomes -1, passes a >= PVCALLS_NR_RSP_PER_RING test and indexes bedata->rsp[-1]. Declare req_id as u32 so a single bound covers both ends. A backend that sends an out-of-range req_id has violated the wire protocol, so rather than silently dropping the response, log once and stop trusting the backend: set bedata->disabled. The event handler then ignores further responses, and the request paths that wait for a response return -EIO instead of blocking forever. This mirrors the fatal-error handling xen-netback uses (xenvif_fatal_tx_err()). The pvcalls frontend currently trusts its backend, so this is not a classic-Xen security issue, but it matters for hardening PV frontends against malicious backends (confidential and disaggregated deployments).
CVE-2026-72380
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-2026-72380
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": "2195046bfd69e487d9a76dc47840f15c8412840c",
"lessThan": "72e27ef70a20298e60a1de438f3628c515dea895",
"versionType": "git"
},
{
"status": "affected",
"version": "2195046bfd69e487d9a76dc47840f15c8412840c",
"lessThan": "ede7a60b046d8b7288651c55198574ed7c259da7",
"versionType": "git"
},
{
"status": "affected",
"version": "2195046bfd69e487d9a76dc47840f15c8412840c",
"lessThan": "bc8f2d1c6f7cf6e6551c00eb582baf4b52a04794",
"versionType": "git"
},
{
"status": "affected",
"version": "2195046bfd69e487d9a76dc47840f15c8412840c",
"lessThan": "d1297a9e2fd6ce08678b370d41bc980ca798f809",
"versionType": "git"
},
{
"status": "affected",
"version": "2195046bfd69e487d9a76dc47840f15c8412840c",
"lessThan": "d33846c8dcc06b83b7acdeac1e8bfbb5c0c26cb2",
"versionType": "git"
}
],
"programFiles": [
"drivers/xen/pvcalls-front.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/xen/pvcalls-front.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-72380
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #46515 · Revision 1
- Added to Heist Feed
- Publisher date