{"id":"DEBIAN-CVE-2023-52854","details":"In the Linux kernel, the following vulnerability has been resolved:  padata: Fix refcnt handling in padata_free_shell()  In a high-load arm64 environment, the pcrypt_aead01 test in LTP can lead to system UAF (Use-After-Free) issues. Due to the lengthy analysis of the pcrypt_aead01 function call, I'll describe the problem scenario using a simplified model:  Suppose there's a user of padata named `user_function` that adheres to the padata requirement of calling `padata_free_shell` after `serial()` has been invoked, as demonstrated in the following code:  ```c struct request {     struct padata_priv padata;     struct completion *done; };  void parallel(struct padata_priv *padata) {     do_something(); }  void serial(struct padata_priv *padata) {     struct request *request = container_of(padata,     \t\t\t\tstruct request, \t\t\t\tpadata);     complete(request-\u003edone); }  void user_function() {     DECLARE_COMPLETION(done)     padata-\u003eparallel = parallel;     padata-\u003eserial = serial;     padata_do_parallel();     wait_for_completion(&done);     padata_free_shell(); } ```  In the corresponding padata.c file, there's the following code:  ```c static void padata_serial_worker(struct work_struct *serial_work) {     ...     cnt = 0;      while (!list_empty(&local_list)) {         ...         padata-\u003eserial(padata);         cnt++;     }      local_bh_enable();      if (refcount_sub_and_test(cnt, &pd-\u003erefcnt))         padata_free_pd(pd); } ```  Because of the high system load and the accumulation of unexecuted softirq at this moment, `local_bh_enable()` in padata takes longer to execute than usual. Subsequently, when accessing `pd-\u003erefcnt`, `pd` has already been released by `padata_free_shell()`, resulting in a UAF issue with `pd-\u003erefcnt`.  The fix is straightforward: add `refcount_dec_and_test` before calling `padata_free_pd` in `padata_free_shell`.","modified":"2026-09-15T09:02:49.018400253Z","published":"2024-05-21T16:15:22.377Z","upstream":["CVE-2023-52854"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2023-52854"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.64-1"}]}],"versions":["6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52854.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52854.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52854.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}