CVE-2026-43071 (GCVE-0-2026-43071)
Vulnerability from cvelistv5 – Published: 2026-05-05 15:29 – Updated: 2026-05-08 12:40
VLAI?
Title
dcache: Limit the minimal number of bucket to two
Summary
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.
Severity ?
9.1 (Critical)
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
99d263d4c5b2f541dfacb5391e22e8c91ea982a6 , < 426ef05e82ee52c8d0e95fc0808b7383d8352d73
(git)
Affected: 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 , < ddd57ebce245f9c7e2f6902a6c087d6186d2385d (git) Affected: 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 , < 755b40903eff563768d4d96fd4ef51ec48adde3b (git) Affected: 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 , < 5718df131ab78897a9dd1f2e71c3ba732d4392af (git) Affected: 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 , < 277cedabb0ab86baae83fa58218be13c6d3e5526 (git) Affected: 99d263d4c5b2f541dfacb5391e22e8c91ea982a6 , < f08fe8891c3eeb63b73f9f1f6d97aa629c821579 (git) Affected: d4c96061fddd129778ce8b70fb093aa532f422d0 (git) Affected: be2378cbffe50ce0161f0fdee914adee98af53dc (git) Affected: a8be8af18485f9fade90e1743d940252a39eec84 (git) Affected: b5cf3193759f7cd1cfbeef11f5cf067bbce22e55 (git) |
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|
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{
"containers": {
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"programFiles": [
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"version": "3.17"
},
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
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},
{
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"status": "unaffected",
"version": "6.12.83",
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},
{
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndcache: Limit the minimal number of bucket to two\n\nThere is an OOB read problem on dentry_hashtable when user sets\n\u0027dhash_entries=1\u0027:\n BUG: unable to handle page fault for address: ffff888b30b774b0\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n Oops: Oops: 0000 [#1] SMP PTI\n RIP: 0010:__d_lookup+0x56/0x120\n Call Trace:\n d_lookup.cold+0x16/0x5d\n lookup_dcache+0x27/0xf0\n lookup_one_qstr_excl+0x2a/0x180\n start_dirop+0x55/0xa0\n simple_start_creating+0x8d/0xa0\n debugfs_start_creating+0x8c/0x180\n debugfs_create_dir+0x1d/0x1c0\n pinctrl_init+0x6d/0x140\n do_one_initcall+0x6d/0x3d0\n kernel_init_freeable+0x39f/0x460\n kernel_init+0x2a/0x260\n\nThere will be only one bucket in dentry_hashtable when dhash_entries is\nset as one, and d_hash_shift is calculated as 32 by dcache_init(). Then,\nfollowing process will access more than one buckets(which memory region\nis not allocated) in dentry_hashtable:\n d_lookup\n b = d_hash(hash)\n dentry_hashtable + ((u32)hashlen \u003e\u003e d_hash_shift)\n // The C standard defines the behavior of right shift amounts\n // exceeding the bit width of the operand as undefined. The\n // result of \u0027(u32)hashlen \u003e\u003e d_hash_shift\u0027 becomes \u0027hashlen\u0027,\n // so \u0027b\u0027 will point to an unallocated memory region.\n hlist_bl_for_each_entry_rcu(b)\n hlist_bl_first_rcu(head)\n h-\u003efirst // read OOB!\n\nFix it by limiting the minimal number of dentry_hashtable bucket to two,\nso that \u0027d_hash_shift\u0027 won\u0027t exceeds the bit width of type u32."
}
],
"metrics": [
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
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"url": "https://git.kernel.org/stable/c/ddd57ebce245f9c7e2f6902a6c087d6186d2385d"
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"url": "https://git.kernel.org/stable/c/755b40903eff563768d4d96fd4ef51ec48adde3b"
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{
"url": "https://git.kernel.org/stable/c/5718df131ab78897a9dd1f2e71c3ba732d4392af"
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{
"url": "https://git.kernel.org/stable/c/277cedabb0ab86baae83fa58218be13c6d3e5526"
},
{
"url": "https://git.kernel.org/stable/c/f08fe8891c3eeb63b73f9f1f6d97aa629c821579"
}
],
"title": "dcache: Limit the minimal number of bucket to two",
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"cveId": "CVE-2026-43071",
"datePublished": "2026-05-05T15:29:28.081Z",
"dateReserved": "2026-05-01T14:12:55.982Z",
"dateUpdated": "2026-05-08T12:40:21.054Z",
"state": "PUBLISHED"
},
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"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-43071",
"date": "2026-05-08",
"epss": "0.00024",
"percentile": "0.06984"
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}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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