ghsa-j584-qjqw-5mpw
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
futex: Don't leak robust_list pointer on exec race
sys_get_robust_list() and compat_get_robust_list() use ptrace_may_access() to check if the calling task is allowed to access another task's robust_list pointer. This check is racy against a concurrent exec() in the target process.
During exec(), a task may transition from a non-privileged binary to a privileged one (e.g., setuid binary) and its credentials/memory mappings may change. If get_robust_list() performs ptrace_may_access() before this transition, it may erroneously allow access to sensitive information after the target becomes privileged.
A racy access allows an attacker to exploit a window during which ptrace_may_access() passes before a target process transitions to a privileged state via exec().
For example, consider a non-privileged task T that is about to execute a setuid-root binary. An attacker task A calls get_robust_list(T) while T is still unprivileged. Since ptrace_may_access() checks permissions based on current credentials, it succeeds. However, if T begins exec immediately afterwards, it becomes privileged and may change its memory mappings. Because get_robust_list() proceeds to access T->robust_list without synchronizing with exec() it may read user-space pointers from a now-privileged process.
This violates the intended post-exec access restrictions and could expose sensitive memory addresses or be used as a primitive in a larger exploit chain. Consequently, the race can lead to unauthorized disclosure of information across privilege boundaries and poses a potential security risk.
Take a read lock on signal->exec_update_lock prior to invoking ptrace_may_access() and accessing the robust_list/compat_robust_list. This ensures that the target task's exec state remains stable during the check, allowing for consistent and synchronized validation of credentials.
{
"affected": [],
"aliases": [
"CVE-2025-40341"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-09T16:17:44Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Don\u0027t leak robust_list pointer on exec race\n\nsys_get_robust_list() and compat_get_robust_list() use ptrace_may_access()\nto check if the calling task is allowed to access another task\u0027s\nrobust_list pointer. This check is racy against a concurrent exec() in the\ntarget process.\n\nDuring exec(), a task may transition from a non-privileged binary to a\nprivileged one (e.g., setuid binary) and its credentials/memory mappings\nmay change. If get_robust_list() performs ptrace_may_access() before\nthis transition, it may erroneously allow access to sensitive information\nafter the target becomes privileged.\n\nA racy access allows an attacker to exploit a window during which\nptrace_may_access() passes before a target process transitions to a\nprivileged state via exec().\n\nFor example, consider a non-privileged task T that is about to execute a\nsetuid-root binary. An attacker task A calls get_robust_list(T) while T\nis still unprivileged. Since ptrace_may_access() checks permissions\nbased on current credentials, it succeeds. However, if T begins exec\nimmediately afterwards, it becomes privileged and may change its memory\nmappings. Because get_robust_list() proceeds to access T-\u003erobust_list\nwithout synchronizing with exec() it may read user-space pointers from a\nnow-privileged process.\n\nThis violates the intended post-exec access restrictions and could\nexpose sensitive memory addresses or be used as a primitive in a larger\nexploit chain. Consequently, the race can lead to unauthorized\ndisclosure of information across privilege boundaries and poses a\npotential security risk.\n\nTake a read lock on signal-\u003eexec_update_lock prior to invoking\nptrace_may_access() and accessing the robust_list/compat_robust_list.\nThis ensures that the target task\u0027s exec state remains stable during the\ncheck, allowing for consistent and synchronized validation of\ncredentials.",
"id": "GHSA-j584-qjqw-5mpw",
"modified": "2025-12-09T18:30:36Z",
"published": "2025-12-09T18:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40341"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3b4222494489f6d4b8705a496dab03384b7ca998"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4aced32596ead1820b7dbd8e40d30b30dc1f3ad4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6511984d1aa1360181bcafb1ca75df7f291ef237"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b54082c3ed4dc9821cdf0edb17302355cc5bb45"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b524455a51feb6013df3a5dba3160487b2e8e22a"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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