fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()
In the Linux kernel, the following vulnerability has been resolved: fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching() unregister_fprobe() and unregister_fprobe_async() (used by BPF kprobe-multi) rely on standard RCU grace periods (synchronize_rcu() and call_rcu()) to wait until in-flight fprobe handlers complete before freeing the fprobe. However, if an fprobe handler executes while RCU is not watching (such as in the idle loop or nohz_full extended quiescent states), standard RCU does not track preemption-disabled sections. Consequently, synchronize_rcu() does not wait for those executions, which can lead to a use-after-free if the fprobe is freed immediately after unregistration. Ensure handlers exit early when !rcu_is_watching(). Furthermore, fprobe_fgraph_entry() and fprobe_ftrace_entry() previously used guard(rcu)() and rcu_read_lock(), which invoke lockdep on every hit under CONFIG_PROVE_LOCKING. This adds overhead and can cause lockdep recursion if probed functions interact with lockdep. Since rhltable_lookup() and rhl_for_each_entry_rcu() use rcu_dereference_all_check() (which checks rcu_read_lock_any_held()), holding preemption disabled via rcu_read_lock_sched_notrace() is fully valid and sufficient so long as rcu_is_watching() is true. Define and use guard(rcu_sched_notrace)() across fprobe_ftrace_entry(), fprobe_fgraph_entry(), and fprobe_return(). This eliminates fast-path rcu_read_lock() and lockdep overhead while guaranteeing safe grace period syn
CVE-2026-98861
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-2026-98861
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": "56b4cfcf1518245493c60fd39c56978f508f1816",
"lessThan": "a85d0f00671b4d4527317c10ba018680f7d8d673",
"versionType": "git"
},
{
"status": "affected",
"version": "657b594b2084b39a4bc6d8493aa2140cb00cea49",
"lessThan": "dd4a0d4993633b45470abf6da4ea0ca563402245",
"versionType": "git"
},
{
"status": "affected",
"version": "657b594b2084b39a4bc6d8493aa2140cb00cea49",
"lessThan": "e0a6249190402a28f1e2925a81acf573157d55ef",
"versionType": "git"
},
{
"status": "affected",
"version": "a4f6a9005ed6cfd360ef2520430927f05f92ffb0",
"versionType": "git"
},
{
"status": "affected",
"version": "6.18.34",
"lessThan": "6.18.56",
"versionType": "semver"
},
{
"status": "affected",
"version": "7.0.11",
"lessThan": "7.1",
"versionType": "semver"
}
],
"programFiles": [
"kernel/trace/fprobe.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.1",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.56",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/trace/fprobe.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98861
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38755 · Revision 1
- Added to Heist Feed
- Publisher date