UBUNTU-CVE-2025-71078
In the Linux kernel, the following vulnerability has been resolved: powerpc/64s/slb: Fix SLB multihit issue during SLB preload On systems using the hash MMU, there is a software SLB preload cache that mirrors the entries loaded into the hardware SLB buffer. This preload cache is subject to periodic eviction — typically after every 256 context switches — to remove old entry. To optimize performance, the kernel skips switch_mmu_context() in switch_mm_irqs_off() when the prev and next mm_struct are the same. However, on hash MMU systems, this can lead to inconsistencies between the hardware SLB and the software preload cache. If an SLB entry for a process is evicted from the software cache on one CPU, and the same process later runs on another CPU without executing switch_mmu_context(), the hardware SLB may retain stale entries. If the kernel then attempts to reload that entry, it can trigger an SLB multi-hit error. The following timeline shows how stale SLB entries are created and can cause a multi-hit error when a process moves between CPUs without a MMU context switch. CPU 0 CPU 1 ----- ----- Process P exec swapper/1 load_elf_binary begin_new_exc activate_mm switch_mm_irqs_off switch_mmu_context switch_slb /* * This invalidates all * the entries in the HW * and setup the new HW * SLB entries as per the * preload cache. */ context_switch sched_migrate_task migrates process P to cpu-1 Process swapper/0 context switch (to process P) (uses mm_struct of Process P) switch_mm_irqs_off() switch_slb load_slb++ /* * load_slb becomes 0 here * and we evict an entry from * the preload cache with * preload_age(). We still * keep HW SLB and preload * cache in sync, that is * because all HW SLB entries * anyways gets evicted in * switch_slb during SLBIA. * We then only add those * entries back in HW SLB, * which are currently * present in preload_cache * (after eviction). */ load_elf_binary continues... setup_new_exec() slb_setup_new_exec() sched_switch event sched_migrate_task migrates process P to cpu-0 context_switch from swapper/0 to Process P switch_mm_irqs_off() /* * Since both prev and next mm struct are same we don't call * switch_mmu_context(). This will cause the HW SLB and SW preload * cache to go out of sync in preload_new_slb_context. Because there * was an SLB entry which was evicted from both HW and preload cache * on cpu-1. Now later in preload_new_slb_context(), when we will try * to add the same preload entry again, we will add this to the SW * preload cache and then will add it to the HW SLB. Since on cpu-0 * this entry was never invalidated, hence adding this entry to the HW * SLB will cause a SLB multi-hit error. */ load_elf_binary cont ---truncated---
02 / AFFECTED SOFTWARE
Affected packages
11 explicit affected versions
53 explicit affected versions
116 explicit affected versions
80 explicit affected versions
50 explicit affected versions
6 explicit affected versions
12 explicit affected versions
19 explicit affected versions
10 explicit affected versions
6 explicit affected versions
90 explicit affected versions
24 explicit affected versions
75 explicit affected versions
75 explicit affected versions
91 explicit affected versions
79 explicit affected versions
70 explicit affected versions
10 explicit affected versions
32 explicit affected versions
26 explicit affected versions
82 explicit affected versions
7 explicit affected versions
77 explicit affected versions
35 explicit affected versions
13 explicit affected versions
39 explicit affected versions
35 explicit affected versions
42 explicit affected versions
40 explicit affected versions
18 explicit affected versions
35 explicit affected versions
64 explicit affected versions
40 explicit affected versions
120 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
47 explicit affected versions
124 explicit affected versions
1 explicit affected versions
21 explicit affected versions
9 explicit affected versions
16 explicit affected versions
10 explicit affected versions
15 explicit affected versions
76 explicit affected versions
43 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
14 explicit affected versions
10 explicit affected versions
1 explicit affected versions
7 explicit affected versions
11 explicit affected versions
104 explicit affected versions
12 explicit affected versions
4 explicit affected versions
105 explicit affected versions
12 explicit affected versions
36 explicit affected versions
36 explicit affected versions
16 explicit affected versions
12 explicit affected versions
25 explicit affected versions
29 explicit affected versions
10 explicit affected versions
37 explicit affected versions
10 explicit affected versions
4 explicit affected versions
13 explicit affected versions
35 explicit affected versions
3 explicit affected versions
10 explicit affected versions
11 explicit affected versions
57 explicit affected versions
1 explicit affected versions
26 explicit affected versions
6 explicit affected versions
13 explicit affected versions
29 explicit affected versions
29 explicit affected versions
111 explicit affected versions
13 explicit affected versions
12 explicit affected versions
87 explicit affected versions
36 explicit affected versions
36 explicit affected versions
3 explicit affected versions
100 explicit affected versions
82 explicit affected versions
45 explicit affected versions
33 explicit affected versions
23 explicit affected versions
51 explicit affected versions
10 explicit affected versions
15 explicit affected versions
14 explicit affected versions
11 explicit affected versions
5 explicit affected versions
12 explicit affected versions
4 explicit affected versions
7 explicit affected versions
12 explicit affected versions
3 explicit affected versions
11 explicit affected versions
5 explicit affected versions
67 explicit affected versions
83 explicit affected versions
10 explicit affected versions
26 explicit affected versions
34 explicit affected versions
1 explicit affected versions
59 explicit affected versions
30 explicit affected versions
42 explicit affected versions
11 explicit affected versions
4 explicit affected versions
13 explicit affected versions
41 explicit affected versions
78 explicit affected versions
16 explicit affected versions
81 explicit affected versions
45 explicit affected versions
3 explicit affected versions
132 explicit affected versions
1 explicit affected versions
7 explicit affected versions
2 explicit affected versions
10 explicit affected versions
51 explicit affected versions
11 explicit affected versions
18 explicit affected versions
37 explicit affected versions
12 explicit affected versions
66 explicit affected versions
70 explicit affected versions
3 explicit affected versions
27 explicit affected versions
56 explicit affected versions
121 explicit affected versions
1 explicit affected versions
38 explicit affected versions
8 explicit affected versions
47 explicit affected versions
5 explicit affected versions
8 explicit affected versions
1 explicit affected versions
10 explicit affected versions
7 explicit affected versions
41 explicit affected versions
13 explicit affected versions
110 explicit affected versions
13 explicit affected versions
72 explicit affected versions
7 explicit affected versions
8 explicit affected versions
10 explicit affected versions
12 explicit affected versions
9 explicit affected versions
30 explicit affected versions
108 explicit affected versions
80 explicit affected versions
56 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
45 explicit affected versions
37 explicit affected versions
46 explicit affected versions
14 explicit affected versions
38 explicit affected versions
9 explicit affected versions
12 explicit affected versions
11 explicit affected versions
34 explicit affected versions
15 explicit affected versions
9 explicit affected versions
83 explicit affected versions
8 explicit affected versions
7 explicit affected versions
4 explicit affected versions
72 explicit affected versions
3 explicit affected versions
1 explicit affected versions
1 explicit affected versions
1 explicit affected versions
81 explicit affected versions
72 explicit affected versions
71 explicit affected versions
13 explicit affected versions
43 explicit affected versions
77 explicit affected versions
9 explicit affected versions
119 explicit affected versions
10 explicit affected versions
8 explicit affected versions
40 explicit affected versions
88 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
9 explicit affected versions
11 explicit affected versions
1 explicit affected versions
123 explicit affected versions
14 explicit affected versions
34 explicit affected versions
71 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: powerpc/64s/slb: Fix SLB multihit issue during SLB preload On systems using the hash MMU, there is a software SLB preload cache that mirrors the entries loaded into the hardware SLB buffer. This preload cache is subject to periodic eviction — typically after every 256 context switches — to remove old entry. To optimize performance, the kernel skips switch_mmu_context() in switch_mm_irqs_off() when the prev and next mm_struct are the same. However, on hash MMU systems, this can lead to inconsistencies between the hardware SLB and the software preload cache. If an SLB entry for a process is evicted from the software cache on one CPU, and the same process later runs on another CPU without executing switch_mmu_context(), the hardware SLB may retain stale entries. If the kernel then attempts to reload that entry, it can trigger an SLB multi-hit error. The following timeline shows how stale SLB entries are created and can cause a multi-hit error when a process moves between CPUs without a MMU context switch. CPU 0 CPU 1 ----- ----- Process P exec swapper/1 load_elf_binary begin_new_exc activate_mm switch_mm_irqs_off switch_mmu_context switch_slb /* * This invalidates all * the entries in the HW * and setup the new HW * SLB entries as per the * preload cache. */ context_switch sched_migrate_task migrates process P to cpu-1 Process swapper/0 context switch (to process P) (uses mm_struct of Process P) switch_mm_irqs_off() switch_slb load_slb++ /* * load_slb becomes 0 here * and we evict an entry from * the preload cache with * preload_age(). We still * keep HW SLB and preload * cache in sync, that is * because all HW SLB entries * anyways gets evicted in * switch_slb during SLBIA. * We then only add those * entries back in HW SLB, * which are currently * present in preload_cache * (after eviction). */ load_elf_binary continues... setup_new_exec() slb_setup_new_exec() sched_switch event sched_migrate_task migrates process P to cpu-0 context_switch from swapper/0 to Process P switch_mm_irqs_off() /* * Since both prev and next mm struct are same we don't call * switch_mmu_context(). This will cause the HW SLB and SW preload * cache to go out of sync in preload_new_slb_context. Because there * was an SLB entry which was evicted from both HW and preload cache * on cpu-1. Now later in preload_new_slb_context(), when we will try * to add the same preload entry again, we will add this to the SW * preload cache and then will add it to the HW SLB. Since on cpu-0 * this entry was never invalidated, hence adding this entry to the HW * SLB will cause a SLB multi-hit error. */ load_elf_binary cont ---truncated---
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/00312419f0863964625d6dcda8183f96849412c6
- https://git.kernel.org/stable/c/00312419f0863964625d6dcda8183f96849412c6
- https://git.kernel.org/stable/c/4ae1e46d8a290319f33f71a2710a1382ba5431e8
- https://git.kernel.org/stable/c/895123c309a34d2cfccf7812b41e17261a3a6f37
- https://git.kernel.org/stable/c/b13a3dbfa196af68eae2031f209743735ad416bf
- https://git.kernel.org/stable/c/c9f865022a1823d814032a09906e91e4701a35fc
- https://ubuntu.com/security/CVE-2025-71078
- https://ubuntu.com/security/notices/USN-8096-1
- https://ubuntu.com/security/notices/USN-8096-2
- https://ubuntu.com/security/notices/USN-8096-3
- https://ubuntu.com/security/notices/USN-8096-4
- https://ubuntu.com/security/notices/USN-8096-5
- https://ubuntu.com/security/notices/USN-8116-1
- https://ubuntu.com/security/notices/USN-8141-1
- https://ubuntu.com/security/notices/USN-8163-1
- https://ubuntu.com/security/notices/USN-8163-2
- https://ubuntu.com/security/notices/USN-8177-1
- https://ubuntu.com/security/notices/USN-8177-2
- https://ubuntu.com/security/notices/USN-8179-1
- https://ubuntu.com/security/notices/USN-8179-2
- https://ubuntu.com/security/notices/USN-8179-3
- https://ubuntu.com/security/notices/USN-8179-4
- https://ubuntu.com/security/notices/USN-8183-1
- https://ubuntu.com/security/notices/USN-8183-2
- https://ubuntu.com/security/notices/USN-8184-1
- https://ubuntu.com/security/notices/USN-8185-1
- https://ubuntu.com/security/notices/USN-8185-2
- https://ubuntu.com/security/notices/USN-8203-1
- https://ubuntu.com/security/notices/USN-8204-1
- https://ubuntu.com/security/notices/USN-8243-1
- https://ubuntu.com/security/notices/USN-8245-1
- https://ubuntu.com/security/notices/USN-8257-1
- https://ubuntu.com/security/notices/USN-8258-1
- https://ubuntu.com/security/notices/USN-8260-1
- https://ubuntu.com/security/notices/USN-8261-1
- https://ubuntu.com/security/notices/USN-8265-1
- https://ubuntu.com/security/notices/USN-8440-1
- https://www.cve.org/CVERecord?id=CVE-2025-71078