{"id":"CVE-2022-48892","summary":"sched/core: Fix use-after-free bug in dup_user_cpus_ptr()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/core: Fix use-after-free bug in dup_user_cpus_ptr()\n\nSince commit 07ec77a1d4e8 (\"sched: Allow task CPU affinity to be\nrestricted on asymmetric systems\"), the setting and clearing of\nuser_cpus_ptr are done under pi_lock for arm64 architecture. However,\ndup_user_cpus_ptr() accesses user_cpus_ptr without any lock\nprotection. Since sched_setaffinity() can be invoked from another\nprocess, the process being modified may be undergoing fork() at\nthe same time.  When racing with the clearing of user_cpus_ptr in\n__set_cpus_allowed_ptr_locked(), it can lead to user-after-free and\npossibly double-free in arm64 kernel.\n\nCommit 8f9ea86fdf99 (\"sched: Always preserve the user requested\ncpumask\") fixes this problem as user_cpus_ptr, once set, will never\nbe cleared in a task's lifetime. However, this bug was re-introduced\nin commit 851a723e45d1 (\"sched: Always clear user_cpus_ptr in\ndo_set_cpus_allowed()\") which allows the clearing of user_cpus_ptr in\ndo_set_cpus_allowed(). This time, it will affect all arches.\n\nFix this bug by always clearing the user_cpus_ptr of the newly\ncloned/forked task before the copying process starts and check the\nuser_cpus_ptr state of the source task under pi_lock.\n\nNote to stable, this patch won't be applicable to stable releases.\nJust copy the new dup_user_cpus_ptr() function over.","modified":"2026-04-02T08:27:07.178776Z","published":"2024-08-21T06:10:24.407Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/48xxx/CVE-2022-48892.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/7b5cc7fd1789ea5dbb942c9f8207b076d365badc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/87ca4f9efbd7cc649ff43b87970888f2812945b8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b22faa21b6230d5eccd233e1b7e0026a5002b287"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/48xxx/CVE-2022-48892.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2022-48892"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"07ec77a1d4e82526e1588979fff2f024f8e96df2"},{"fixed":"b22faa21b6230d5eccd233e1b7e0026a5002b287"},{"fixed":"7b5cc7fd1789ea5dbb942c9f8207b076d365badc"},{"fixed":"87ca4f9efbd7cc649ff43b87970888f2812945b8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-48892.json"}}],"schema_version":"1.7.5"}