bpf: Defer work in bpf_timer_cancel_and_free
In the Linux kernel, the following vulnerability has been resolved: bpf: Defer work in bpf_timer_cancel_and_free Currently, the same case as previous patch (two timer callbacks trying to cancel each other) can be invoked through bpf_map_update_elem as well, or more precisely, freeing map elements containing timers. Since this relies on hrtimer_cancel as well, it is prone to the same deadlock situation as the previous patch. It would be sufficient to use hrtimer_try_to_cancel to fix this problem, as the timer cannot be enqueued after async_cancel_and_free. Once async_cancel_and_free has been done, the timer must be reinitialized before it can be armed again. The callback running in parallel trying to arm the timer will fail, and freeing bpf_hrtimer without waiting is sufficient (given kfree_rcu), and bpf_timer_cb will return HRTIMER_NORESTART, preventing the timer from being rearmed again. However, there exists a UAF scenario where the callback arms the timer before entering this function, such that if cancellation fails (due to timer callback invoking this routine, or the target timer callback running concurrently). In such a case, if the timer expiration is significantly far in the future, the RCU grace period expiration happening before it will free the bpf_hrtimer state and along with it the struct hrtimer, that is enqueued. Hence, it is clear cancellation needs to occur after async_cancel_and_free, and yet it cannot be done inline due to deadlock issues. We thus modify bp
CVE-2024-41045
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-2024-41045
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": "b00628b1c7d595ae5b544e059c27b1f5828314b4",
"lessThan": "5eaa11c500ed07f505f86cec07d5593a71927e26",
"versionType": "git"
},
{
"status": "affected",
"version": "b00628b1c7d595ae5b544e059c27b1f5828314b4",
"lessThan": "7aa5a19279c3639ae8b758b63f05d0c616a39fa1",
"versionType": "git"
},
{
"status": "affected",
"version": "b00628b1c7d595ae5b544e059c27b1f5828314b4",
"lessThan": "a6fcd19d7eac1335eb76bc16b6a66b7f574d1d69",
"versionType": "git"
}
],
"programFiles": [
"kernel/bpf/helpers.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.9.10",
"versionType": "semver",
"lessThanOrEqual": "6.9.*"
},
{
"status": "unaffected",
"version": "6.10",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/bpf/helpers.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2024-41045
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #8225 · Revision 1
- Added to Heist Feed
- Publisher date