Bugzilla – Bug 1220941
VUL-0: CVE-2023-52568: kernel: x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race
Last modified: 2024-06-25 18:17:04 UTC
In the Linux kernel, the following vulnerability has been resolved: x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race The SGX EPC reclaimer (ksgxd) may reclaim the SECS EPC page for an enclave and set secs.epc_page to NULL. The SECS page is used for EAUG and ELDU in the SGX page fault handler. However, the NULL check for secs.epc_page is only done for ELDU, not EAUG before being used. Fix this by doing the same NULL check and reloading of the SECS page as needed for both EAUG and ELDU. The SECS page holds global enclave metadata. It can only be reclaimed when there are no other enclave pages remaining. At that point, virtually nothing can be done with the enclave until the SECS page is paged back in. An enclave can not run nor generate page faults without a resident SECS page. But it is still possible for a #PF for a non-SECS page to race with paging out the SECS page: when the last resident non-SECS page A triggers a #PF in a non-resident page B, and then page A and the SECS both are paged out before the #PF on B is handled. Hitting this bug requires that race triggered with a #PF for EAUG. Following is a trace when it happens. BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:sgx_encl_eaug_page+0xc7/0x210 Call Trace: ? __kmem_cache_alloc_node+0x16a/0x440 ? xa_load+0x6e/0xa0 sgx_vma_fault+0x119/0x230 __do_fault+0x36/0x140 do_fault+0x12f/0x400 __handle_mm_fault+0x728/0x1110 handle_mm_fault+0x105/0x310 do_user_addr_fault+0x1ee/0x750 ? __this_cpu_preempt_check+0x13/0x20 exc_page_fault+0x76/0x180 asm_exc_page_fault+0x27/0x30 References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-52568 https://git.kernel.org/stable/c/c6c2adcba50c2622ed25ba5d5e7f05f584711358 https://www.cve.org/CVERecord?id=CVE-2023-52568 https://git.kernel.org/stable/c/1348f7f15d7c7798456856bee74a4235c2da994e https://git.kernel.org/stable/c/811ba2ef0cb6402672e64ba1419d6ef95aa3405d https://bugzilla.redhat.com/show_bug.cgi?id=2267740
Offending commit (5a90d2c3f5ef) found in: - SLE15-SP6 - stable Only stable has the fix (811ba2ef0cb6), tracking SLE15-SP6 as affected.
Jiri, this seems to be in your area.
FTR commit c6c2adcba50c2622ed25ba5d5e7f05f584711358 Author: Haitao Huang <haitao.huang@linux.intel.com> Date: Thu Jul 27 22:10:24 2023 -0700 x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race in v6.6-rc4 Fixes: 5a90d2c3f5ef ("x86/sgx: Support adding of pages to an initialized enclave") in v6.0-rc1
Pushed to 15-sp6.
All done, closing.