UBUNTU-CVE-2025-21851
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix softlockup in arena_map_free on 64k page kernel On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64. It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup. Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.
02 / AFFECTED SOFTWARE
Affected packages
11 explicit affected versions
50 explicit affected versions
6 explicit affected versions
12 explicit affected versions
19 explicit affected versions
6 explicit affected versions
10 explicit affected versions
7 explicit affected versions
13 explicit affected versions
35 explicit affected versions
18 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
1 explicit affected versions
21 explicit affected versions
16 explicit affected versions
10 explicit affected versions
5 explicit affected versions
7 explicit affected versions
12 explicit affected versions
4 explicit affected versions
12 explicit affected versions
14 explicit affected versions
1 explicit affected versions
7 explicit affected versions
12 explicit affected versions
12 explicit affected versions
10 explicit affected versions
37 explicit affected versions
13 explicit affected versions
10 explicit affected versions
26 explicit affected versions
13 explicit affected versions
29 explicit affected versions
13 explicit affected versions
33 explicit affected versions
23 explicit affected versions
10 explicit affected versions
12 explicit affected versions
7 explicit affected versions
12 explicit affected versions
10 explicit affected versions
26 explicit affected versions
13 explicit affected versions
16 explicit affected versions
3 explicit affected versions
4 explicit affected versions
51 explicit affected versions
13 explicit affected versions
12 explicit affected versions
27 explicit affected versions
8 explicit affected versions
5 explicit affected versions
8 explicit affected versions
10 explicit affected versions
4 explicit affected versions
13 explicit affected versions
13 explicit affected versions
7 explicit affected versions
3 explicit affected versions
10 explicit affected versions
12 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
14 explicit affected versions
38 explicit affected versions
9 explicit affected versions
11 explicit affected versions
7 explicit affected versions
4 explicit affected versions
1 explicit affected versions
13 explicit affected versions
43 explicit affected versions
10 explicit affected versions
8 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix softlockup in arena_map_free on 64k page kernel On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64. It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup. Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/517e8a7835e8cfb398a0aeb0133de50e31cae32b
- https://git.kernel.org/stable/c/517e8a7835e8cfb398a0aeb0133de50e31cae32b
- https://git.kernel.org/stable/c/787d556a3de447e70964a4bdeba9196f62a62b1e
- https://git.kernel.org/stable/c/c1f3f3892d4526f18aaeffdb6068ce861e793ee3
- https://ubuntu.com/security/CVE-2025-21851
- https://ubuntu.com/security/notices/USN-7521-1
- https://ubuntu.com/security/notices/USN-7521-2
- https://ubuntu.com/security/notices/USN-7521-3
- https://www.cve.org/CVERecord?id=CVE-2025-21851