# CVE-2022-48731: linux: In the Linux kernel, the following vulnerability has been resolved:  mm/kmemleak: avoid scanning potential huge holes...

CVE-2022-48731 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-48731, released June 20, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-48731
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 20, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  mm/kmemleak: avoid scanning potential huge holes  When using devm_request_free_mem_region() and devm_memremap_pages() to add ZONE_DEVICE memory, if requested free mem region's end pfn were huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see move_pfn_range_to_zone()).  Thus it creates a huge hole between node_start_pfn() and node_end_pfn().  We found on some AMD APUs, amdkfd requested such a free mem region and created a huge hole.  In such a case, following code snippet was just doing busy test_bit() looping on the huge hole.    for (pfn = start_pfn; pfn < end_pfn; pfn++) { 	struct page *page = pfn_to_online_page(pfn); 		if (!page) 			continue; 	...   }  So we got a soft lockup:    watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221]   CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1   RIP: 0010:pfn_to_online_page+0x5/0xd0   Call Trace:     ? kmemleak_scan+0x16a/0x440     kmemleak_write+0x306/0x3a0     ? common_file_perm+0x72/0x170     full_proxy_write+0x5c/0x90     vfs_write+0xb9/0x260     ksys_write+0x67/0xe0     __x64_sys_write+0x1a/0x20     do_syscall_64+0x3b/0xc0     entry_SYSCALL_64_after_hwframe+0x44/0xae  I did some tests with the patch.  (1) amdgpu module unloaded  before the patch:    real    0m0.976s   user    0m0.000s   sys     0m0.968s  after the patch:    real    0m0.981s   user    0m0.000s   sys     0m0.973s  (2) amdgpu module loaded  before the patch:    real    0m35.365s   user    0m0.000s   sys     0m35.354s  after the patch:    real    0m1.049s   user    0m0.000s   sys     0m1.042s

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.16.10-1 | [DEBIAN-CVE-2022-48731](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48731.md) | Jun 20, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.16.10-1 | [DEBIAN-CVE-2022-48731](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48731.md) | Jun 20, 2024 |
| Linux | linux Debian 14 | 5.16.10-1 | [DEBIAN-CVE-2022-48731](https://patchblox.com/security/data/fix/linux/debian-cve-2022-48731.md) | Jun 20, 2024 |

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