UBUNTU-CVE-2025-38334
In the Linux kernel, the following vulnerability has been resolved: x86/sgx: Prevent attempts to reclaim poisoned pages TL;DR: SGX page reclaim touches the page to copy its contents to secondary storage. SGX instructions do not gracefully handle machine checks. Despite this, the existing SGX code will try to reclaim pages that it _knows_ are poisoned. Avoid even trying to reclaim poisoned pages. The longer story: Pages used by an enclave only get epc_page->poison set in arch_memory_failure() but they currently stay on sgx_active_page_list until sgx_encl_release(), with the SGX_EPC_PAGE_RECLAIMER_TRACKED flag untouched. epc_page->poison is not checked in the reclaimer logic meaning that, if other conditions are met, an attempt will be made to reclaim an EPC page that was poisoned. This is bad because 1. we don't want that page to end up added to another enclave and 2. it is likely to cause one core to shut down and the kernel to panic. Specifically, reclaiming uses microcode operations including "EWB" which accesses the EPC page contents to encrypt and write them out to non-SGX memory. Those operations cannot handle MCEs in their accesses other than by putting the executing core into a special shutdown state (affecting both threads with HT.) The kernel will subsequently panic on the remaining cores seeing the core didn't enter MCE handler(s) in time. Call sgx_unmark_page_reclaimable() to remove the affected EPC page from sgx_active_page_list on memory error to stop it being considered for reclaiming. Testing epc_page->poison in sgx_reclaim_pages() would also work but I assume it's better to add code in the less likely paths. The affected EPC page is not added to &node->sgx_poison_page_list until later in sgx_encl_release()->sgx_free_epc_page() when it is EREMOVEd. Membership on other lists doesn't change to avoid changing any of the lists' semantics except for sgx_active_page_list. There's a "TBD" comment in arch_memory_failure() about pre-emptive actions, the goal here is not to address everything that it may imply. This also doesn't completely close the time window when a memory error notification will be fatal (for a not previously poisoned EPC page) -- the MCE can happen after sgx_reclaim_pages() has selected its candidates or even *inside* a microcode operation (actually easy to trigger due to the amount of time spent in them.) The spinlock in sgx_unmark_page_reclaimable() is safe because memory_failure() runs in process context and no spinlocks are held, explicitly noted in a mm/memory-failure.c comment.
02 / AFFECTED SOFTWARE
Affected packages
124 explicit affected versions
1 explicit affected versions
1 explicit affected versions
21 explicit affected versions
1 explicit affected versions
69 explicit affected versions
26 explicit affected versions
10 explicit affected versions
13 explicit affected versions
26 explicit affected versions
1 explicit affected versions
32 explicit affected versions
111 explicit affected versions
12 explicit affected versions
13 explicit affected versions
110 explicit affected versions
139 explicit affected versions
78 explicit affected versions
92 explicit affected versions
98 explicit affected versions
8 explicit affected versions
1 explicit affected versions
10 explicit affected versions
7 explicit affected versions
37 explicit affected versions
37 explicit affected versions
42 explicit affected versions
1 explicit affected versions
1 explicit affected versions
1 explicit affected versions
91 explicit affected versions
80 explicit affected versions
79 explicit affected versions
13 explicit affected versions
43 explicit affected versions
30 explicit affected versions
11 explicit affected versions
53 explicit affected versions
116 explicit affected versions
7 explicit affected versions
11 explicit affected versions
12 explicit affected versions
7 explicit affected versions
188 explicit affected versions
31 explicit affected versions
89 explicit affected versions
50 explicit affected versions
6 explicit affected versions
12 explicit affected versions
19 explicit affected versions
6 explicit affected versions
100 explicit affected versions
61 explicit affected versions
24 explicit affected versions
84 explicit affected versions
85 explicit affected versions
91 explicit affected versions
86 explicit affected versions
76 explicit affected versions
10 explicit affected versions
28 explicit affected versions
26 explicit affected versions
90 explicit affected versions
191 explicit affected versions
120 explicit affected versions
84 explicit affected versions
32 explicit affected versions
13 explicit affected versions
85 explicit affected versions
35 explicit affected versions
35 explicit affected versions
51 explicit affected versions
50 explicit affected versions
18 explicit affected versions
42 explicit affected versions
118 explicit affected versions
64 explicit affected versions
37 explicit affected versions
13 explicit affected versions
4 explicit affected versions
121 explicit affected versions
23 explicit affected versions
43 explicit affected versions
7 explicit affected versions
9 explicit affected versions
16 explicit affected versions
10 explicit affected versions
76 explicit affected versions
39 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
14 explicit affected versions
10 explicit affected versions
37 explicit affected versions
1 explicit affected versions
7 explicit affected versions
9 explicit affected versions
104 explicit affected versions
12 explicit affected versions
105 explicit affected versions
12 explicit affected versions
32 explicit affected versions
120 explicit affected versions
45 explicit affected versions
9 explicit affected versions
23 explicit affected versions
25 explicit affected versions
10 explicit affected versions
31 explicit affected versions
2 explicit affected versions
10 explicit affected versions
7 explicit affected versions
68 explicit affected versions
1 explicit affected versions
3 explicit affected versions
13 explicit affected versions
144 explicit affected versions
37 explicit affected versions
29 explicit affected versions
111 explicit affected versions
13 explicit affected versions
8 explicit affected versions
96 explicit affected versions
32 explicit affected versions
1 explicit affected versions
100 explicit affected versions
92 explicit affected versions
10 explicit affected versions
55 explicit affected versions
33 explicit affected versions
23 explicit affected versions
60 explicit affected versions
10 explicit affected versions
11 explicit affected versions
12 explicit affected versions
7 explicit affected versions
138 explicit affected versions
2 explicit affected versions
3 explicit affected versions
77 explicit affected versions
132 explicit affected versions
93 explicit affected versions
165 explicit affected versions
154 explicit affected versions
10 explicit affected versions
26 explicit affected versions
38 explicit affected versions
7 explicit affected versions
13 explicit affected versions
37 explicit affected versions
16 explicit affected versions
91 explicit affected versions
41 explicit affected versions
116 explicit affected versions
3 explicit affected versions
132 explicit affected versions
93 explicit affected versions
1 explicit affected versions
7 explicit affected versions
2 explicit affected versions
51 explicit affected versions
18 explicit affected versions
33 explicit affected versions
12 explicit affected versions
71 explicit affected versions
80 explicit affected versions
27 explicit affected versions
66 explicit affected versions
121 explicit affected versions
1 explicit affected versions
1 explicit affected versions
34 explicit affected versions
8 explicit affected versions
55 explicit affected versions
5 explicit affected versions
3 explicit affected versions
13 explicit affected versions
72 explicit affected versions
7 explicit affected versions
140 explicit affected versions
8 explicit affected versions
94 explicit affected versions
10 explicit affected versions
12 explicit affected versions
5 explicit affected versions
36 explicit affected versions
39 explicit affected versions
108 explicit affected versions
80 explicit affected versions
56 explicit affected versions
44 explicit affected versions
11 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
45 explicit affected versions
14 explicit affected versions
38 explicit affected versions
167 explicit affected versions
9 explicit affected versions
11 explicit affected versions
30 explicit affected versions
13 explicit affected versions
92 explicit affected versions
8 explicit affected versions
7 explicit affected versions
97 explicit affected versions
121 explicit affected versions
4 explicit affected versions
81 explicit affected versions
77 explicit affected versions
119 explicit affected versions
10 explicit affected versions
8 explicit affected versions
88 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
1 explicit affected versions
69 explicit affected versions
123 explicit affected versions
10 explicit affected versions
80 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: x86/sgx: Prevent attempts to reclaim poisoned pages TL;DR: SGX page reclaim touches the page to copy its contents to secondary storage. SGX instructions do not gracefully handle machine checks. Despite this, the existing SGX code will try to reclaim pages that it _knows_ are poisoned. Avoid even trying to reclaim poisoned pages. The longer story: Pages used by an enclave only get epc_page->poison set in arch_memory_failure() but they currently stay on sgx_active_page_list until sgx_encl_release(), with the SGX_EPC_PAGE_RECLAIMER_TRACKED flag untouched. epc_page->poison is not checked in the reclaimer logic meaning that, if other conditions are met, an attempt will be made to reclaim an EPC page that was poisoned. This is bad because 1. we don't want that page to end up added to another enclave and 2. it is likely to cause one core to shut down and the kernel to panic. Specifically, reclaiming uses microcode operations including "EWB" which accesses the EPC page contents to encrypt and write them out to non-SGX memory. Those operations cannot handle MCEs in their accesses other than by putting the executing core into a special shutdown state (affecting both threads with HT.) The kernel will subsequently panic on the remaining cores seeing the core didn't enter MCE handler(s) in time. Call sgx_unmark_page_reclaimable() to remove the affected EPC page from sgx_active_page_list on memory error to stop it being considered for reclaiming. Testing epc_page->poison in sgx_reclaim_pages() would also work but I assume it's better to add code in the less likely paths. The affected EPC page is not added to &node->sgx_poison_page_list until later in sgx_encl_release()->sgx_free_epc_page() when it is EREMOVEd. Membership on other lists doesn't change to avoid changing any of the lists' semantics except for sgx_active_page_list. There's a "TBD" comment in arch_memory_failure() about pre-emptive actions, the goal here is not to address everything that it may imply. This also doesn't completely close the time window when a memory error notification will be fatal (for a not previously poisoned EPC page) -- the MCE can happen after sgx_reclaim_pages() has selected its candidates or even *inside* a microcode operation (actually easy to trigger due to the amount of time spent in them.) The spinlock in sgx_unmark_page_reclaimable() is safe because memory_failure() runs in process context and no spinlocks are held, explicitly noted in a mm/memory-failure.c comment.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/ed16618c380c32c68c06186d0ccbb0d5e0586e59
- https://git.kernel.org/stable/c/00a88e9ea1b170d579c56327c38f7e8cf689df87
- https://git.kernel.org/stable/c/31dcbac94bfeabb86bf85b0c36803fdd6536437b
- https://git.kernel.org/stable/c/62b62a2a6dc51ed6e8e334861f04220c9cf8106a
- https://git.kernel.org/stable/c/dc5de5bd6deabd327ced2b2b1d0b4f14cd146afe
- https://git.kernel.org/stable/c/ed16618c380c32c68c06186d0ccbb0d5e0586e59
- https://ubuntu.com/security/CVE-2025-38334
- https://ubuntu.com/security/notices/USN-7833-1
- https://ubuntu.com/security/notices/USN-7833-2
- https://ubuntu.com/security/notices/USN-7833-3
- https://ubuntu.com/security/notices/USN-7833-4
- https://ubuntu.com/security/notices/USN-7834-1
- https://ubuntu.com/security/notices/USN-7856-1
- https://ubuntu.com/security/notices/USN-8028-1
- https://ubuntu.com/security/notices/USN-8028-2
- https://ubuntu.com/security/notices/USN-8028-3
- https://ubuntu.com/security/notices/USN-8028-4
- https://ubuntu.com/security/notices/USN-8028-5
- https://ubuntu.com/security/notices/USN-8028-6
- https://ubuntu.com/security/notices/USN-8028-7
- https://ubuntu.com/security/notices/USN-8028-8
- https://ubuntu.com/security/notices/USN-8031-1
- https://ubuntu.com/security/notices/USN-8031-2
- https://ubuntu.com/security/notices/USN-8031-3
- https://ubuntu.com/security/notices/USN-8052-1
- https://ubuntu.com/security/notices/USN-8052-2
- https://ubuntu.com/security/notices/USN-8074-1
- https://ubuntu.com/security/notices/USN-8074-2
- https://ubuntu.com/security/notices/USN-8126-1
- https://www.cve.org/CVERecord?id=CVE-2025-38334