CVE-2026-43071

dcache: Limit the minimal number of bucket to two

State: Published
Severity: 9.1 Critical
Published: May 5, 2026
Updated: Oct 19, 2026
Reserved: May 1, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

dcache: Limit the minimal number of bucket to two

There is an OOB read problem on dentry_hashtable when user sets 'dhash_entries=1': BUG: unable to handle page fault for address: ffff888b30b774b0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP PTI RIP: 0010:__d_lookup+0x56/0x120 Call Trace: d_lookup.cold+0x16/0x5d lookup_dcache+0x27/0xf0 lookup_one_qstr_excl+0x2a/0x180 start_dirop+0x55/0xa0 simple_start_creating+0x8d/0xa0 debugfs_start_creating+0x8c/0x180 debugfs_create_dir+0x1d/0x1c0 pinctrl_init+0x6d/0x140 do_one_initcall+0x6d/0x3d0 kernel_init_freeable+0x39f/0x460 kernel_init+0x2a/0x260

There will be only one bucket in dentry_hashtable when dhash_entries is set as one, and d_hash_shift is calculated as 32 by dcache_init(). Then, following process will access more than one buckets(which memory region is not allocated) in dentry_hashtable: d_lookup b = d_hash(hash) dentry_hashtable + ((u32)hashlen >> d_hash_shift) // The C standard defines the behavior of right shift amounts // exceeding the bit width of the operand as undefined. The // result of '(u32)hashlen >> d_hash_shift' becomes 'hashlen', // so 'b' will point to an unallocated memory region. hlist_bl_for_each_entry_rcu(b) hlist_bl_first_rcu(head) h->first // read OOB!

Fix it by limiting the minimal number of dentry_hashtable bucket to two, so that 'd_hash_shift' won't exceeds the bit width of type u32.

Scores

CVSS	Score	Vector	Source
3.1	9.1 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H	Linux

Weaknesses

CWE-125 Out-of-bounds Read

Affected Products

Product	Versions
LinuxLinux	99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 45b06bb5ea96f75ad81d7ef446f832ea6b0026feAffected 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 426ef05e82ee52c8d0e95fc0808b7383d8352d73Affected 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before ddd57ebce245f9c7e2f6902a6c087d6186d2385dAffected 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 755b40903eff563768d4d96fd4ef51ec48adde3bAffected 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 5718df131ab78897a9dd1f2e71c3ba732d4392afAffected 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 277cedabb0ab86baae83fa58218be13c6d3e5526Affected 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before f08fe8891c3eeb63b73f9f1f6d97aa629c821579Affected d4c96061fddd129778ce8b70fb093aa532f422d0Affected be2378cbffe50ce0161f0fdee914adee98af53dcAffected a8be8af18485f9fade90e1743d940252a39eec84Affected b5cf3193759f7cd1cfbeef11f5cf067bbce22e55Affected 3.10.55 to before 3.11Affected 3.12.29 to before 3.13Affected 3.14.19 to before 3.15Affected 3.16.3 to before 3.17Affected
LinuxLinux	3.17Affected before 3.17Not affected 6.1.175 through 6.1.Not affected 6.6.136 through 6.6.Not affected 6.12.83 through 6.12.Not affected 6.18.24 through 6.18.Not affected 6.19.14 through 6.19.Not affected 7.0.1 through 7.0.Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 45b06bb5ea96f75ad81d7ef446f832ea6b0026feAffected
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 426ef05e82ee52c8d0e95fc0808b7383d8352d73Affected
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before ddd57ebce245f9c7e2f6902a6c087d6186d2385dAffected
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 755b40903eff563768d4d96fd4ef51ec48adde3bAffected
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 5718df131ab78897a9dd1f2e71c3ba732d4392afAffected
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before 277cedabb0ab86baae83fa58218be13c6d3e5526Affected
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 to before f08fe8891c3eeb63b73f9f1f6d97aa629c821579Affected
d4c96061fddd129778ce8b70fb093aa532f422d0Affected
be2378cbffe50ce0161f0fdee914adee98af53dcAffected
a8be8af18485f9fade90e1743d940252a39eec84Affected
b5cf3193759f7cd1cfbeef11f5cf067bbce22e55Affected
3.10.55 to before 3.11Affected
3.12.29 to before 3.13Affected
3.14.19 to before 3.15Affected
3.16.3 to before 3.17Affected

LinuxLinux

3.17Affected
before 3.17Not affected
6.1.175 through 6.1.*Not affected
6.6.136 through 6.6.*Not affected
6.12.83 through 6.12.*Not affected
6.18.24 through 6.18.*Not affected
6.19.14 through 6.19.*Not affected
7.0.1 through 7.0.*Not affected
7.1 and laterNot affected

References

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