UBUNTU-CVE-2025-39817
In the Linux kernel, the following vulnerability has been resolved: efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare Observed on kernel 6.6 (present on master as well): BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasan_check_range+0xe8/0x190 __asan_loadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfs_d_compare+0x68/0xd8 __d_lookup_rcu_op_compare+0x178/0x218 __d_lookup_rcu+0x1f8/0x228 d_alloc_parallel+0x150/0x648 lookup_open.isra.0+0x5f0/0x8d0 open_last_lookups+0x264/0x828 path_openat+0x130/0x3f8 do_filp_open+0x114/0x248 do_sys_openat2+0x340/0x3c0 __arm64_sys_openat+0x120/0x1a0 If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename: T1 T2 lookup_open ->lookup simple_lookup d_add // invalid dentry is added to hash list lookup_open d_alloc_parallel __d_lookup_rcu __d_lookup_rcu_op_compare hlist_bl_for_each_entry_rcu // invalid dentry can be retrieved ->d_compare efivarfs_d_compare // oob Fix it by checking 'guid' before cmp.
02 / AFFECTED SOFTWARE
Affected packages
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13 explicit affected versions
43 explicit affected versions
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119 explicit affected versions
10 explicit affected versions
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38 explicit affected versions
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14 explicit affected versions
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78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
69 explicit affected versions
123 explicit affected versions
12 explicit affected versions
32 explicit affected versions
66 explicit affected versions
11 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare Observed on kernel 6.6 (present on master as well): BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasan_check_range+0xe8/0x190 __asan_loadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfs_d_compare+0x68/0xd8 __d_lookup_rcu_op_compare+0x178/0x218 __d_lookup_rcu+0x1f8/0x228 d_alloc_parallel+0x150/0x648 lookup_open.isra.0+0x5f0/0x8d0 open_last_lookups+0x264/0x828 path_openat+0x130/0x3f8 do_filp_open+0x114/0x248 do_sys_openat2+0x340/0x3c0 __arm64_sys_openat+0x120/0x1a0 If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename: T1 T2 lookup_open ->lookup simple_lookup d_add // invalid dentry is added to hash list lookup_open d_alloc_parallel __d_lookup_rcu __d_lookup_rcu_op_compare hlist_bl_for_each_entry_rcu // invalid dentry can be retrieved ->d_compare efivarfs_d_compare // oob Fix it by checking 'guid' before cmp.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c
- https://git.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6
- https://git.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2
- https://git.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95
- https://git.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410e
- https://git.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40
- https://git.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c
- https://git.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbf
- https://git.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7
- https://ubuntu.com/security/CVE-2025-39817
- https://ubuntu.com/security/notices/USN-7909-1
- https://ubuntu.com/security/notices/USN-7909-2
- https://ubuntu.com/security/notices/USN-7909-3
- https://ubuntu.com/security/notices/USN-7909-4
- https://ubuntu.com/security/notices/USN-7909-5
- https://ubuntu.com/security/notices/USN-7910-1
- https://ubuntu.com/security/notices/USN-7910-2
- https://ubuntu.com/security/notices/USN-7933-1
- https://ubuntu.com/security/notices/USN-7938-1
- https://ubuntu.com/security/notices/USN-8095-1
- https://ubuntu.com/security/notices/USN-8095-2
- https://ubuntu.com/security/notices/USN-8095-3
- https://ubuntu.com/security/notices/USN-8095-4
- https://ubuntu.com/security/notices/USN-8095-5
- https://ubuntu.com/security/notices/USN-8100-1
- https://ubuntu.com/security/notices/USN-8125-1
- https://ubuntu.com/security/notices/USN-8126-1
- https://ubuntu.com/security/notices/USN-8165-1
- https://ubuntu.com/security/notices/USN-8261-1
- https://www.cve.org/CVERecord?id=CVE-2025-39817