CVE-2021-47640
CVE.org · Published
- Record status
- Published
- Identifier year (not publication year)
- 2021
- Source publication
- Source updated
- Imported by cveboard
- Source snapshot
- cve_2026-10-24_midnight_baseline ·
CNA source text (English)
powerpc/kasan: Fix early region not updated correctly
In the Linux kernel, the following vulnerability has been resolved: powerpc/kasan: Fix early region not updated correctly The shadow's page table is not updated when PTE_RPN_SHIFT is 24 and PAGE_SHIFT is 12. It not only causes false positives but also false negative as shown the following text. Fix it by bringing the logic of kasan_early_shadow_page_entry here. 1. False Positive: ================================================================== BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50 Write of size 16 at addr f57f3be0 by task swapper/0/1 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1 Call Trace: [c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable) [c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300 [c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200 [c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0 [c80d1cc0] [c03018a4] memset+0x34/0x90 [c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50 [c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570 [c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0 [c80d1db0] [c2036580] init_sd+0xc4/0x1d0 [c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c [c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384 [c80d1ef0] [c0004b14] kernel_init+0x24/0x170 [c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64 Memory state around the buggy address: f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ================================================================== 2. False Negative (with KASAN tests): ================================================================== Before fix: ok 45 - kmalloc_double_kzfree # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039 KASAN failure expected in "((volatile char *)area)[3100]", but none occurred not ok 46 - vmalloc_oob not ok 1 - kasan ================================================================== After fix: ok 1 - kasan
Scoped product and version facts
Fix information unknown; no fixed version is derived here. Missing information does not prove that no fix exists.
Exploitation unknown; this catalogue does not assess exploitation.
Linux
- Vendor
- Linux
- Product
- Linux
- Platforms
- Unknown
- Default status
unaffected
| Version (version) | Status (status) | Version scheme (versionType) | Exclusive end (lessThan) | Inclusive end (lessThanOrEqual) | Status changes (at → status) |
|---|---|---|---|---|---|
| cbd18991e24fea2c31da3bb117c83e4a3538cd11 | affected | git | 7f19245c3647afea8c7c41f795506ef70f64b9f2 | Unavailable | None listed |
| cbd18991e24fea2c31da3bb117c83e4a3538cd11 | affected | git | f39a3309393a4a484532f6ba745c6acbcfe06115 | Unavailable | None listed |
| cbd18991e24fea2c31da3bb117c83e4a3538cd11 | affected | git | 5a3d8f3192a409893c57808cc935e16484df1068 | Unavailable | None listed |
| cbd18991e24fea2c31da3bb117c83e4a3538cd11 | affected | git | de56beace6648065d404cd9835aa7d30e3df519d | Unavailable | None listed |
| cbd18991e24fea2c31da3bb117c83e4a3538cd11 | affected | git | e3d157a4b4f4e0268c98be5b7013bf4b31234bb6 | Unavailable | None listed |
| cbd18991e24fea2c31da3bb117c83e4a3538cd11 | affected | git | dd75080aa8409ce10d50fb58981c6b59bf8707d3 | Unavailable | None listed |
| 3822dd8c102d11ada9d9ed8e04cad0b347a04689 | affected | git | Unavailable | Unavailable | None listed |
| 5.3.6 | affected | semver | 5.4 | Unavailable | None listed |
Linux
- Vendor
- Linux
- Product
- Linux
- Platforms
- Unknown
- Default status
affected
| Version (version) | Status (status) | Version scheme (versionType) | Exclusive end (lessThan) | Inclusive end (lessThanOrEqual) | Status changes (at → status) |
|---|---|---|---|---|---|
| 5.4 | affected | Unavailable | Unavailable | Unavailable | None listed |
| 0 | unaffected | semver | 5.4 | Unavailable | None listed |
| 5.4.189 | unaffected | semver | Unavailable | 5.4.* | None listed |
| 5.10.110 | unaffected | semver | Unavailable | 5.10.* | None listed |
| 5.15.33 | unaffected | semver | Unavailable | 5.15.* | None listed |
| 5.16.19 | unaffected | semver | Unavailable | 5.16.* | None listed |
| 5.17.2 | unaffected | semver | Unavailable | 5.17.* | None listed |
| 5.18 | unaffected | original_commit_for_fix | Unavailable | * | None listed |