CVE-2025-68198 (GCVE-0-2025-68198)

Vulnerability from cvelistv5 – Published: 2025-12-16 13:48 – Updated: 2026-05-11 21:48
VLAI
Title
crash: fix crashkernel resource shrink
Summary
In the Linux kernel, the following vulnerability has been resolved: crash: fix crashkernel resource shrink When crashkernel is configured with a high reservation, shrinking its value below the low crashkernel reservation causes two issues: 1. Invalid crashkernel resource objects 2. Kernel crash if crashkernel shrinking is done twice For example, with crashkernel=200M,high, the kernel reserves 200MB of high memory and some default low memory (say 256MB). The reservation appears as: cat /proc/iomem | grep -i crash af000000-beffffff : Crash kernel 433000000-43f7fffff : Crash kernel If crashkernel is then shrunk to 50MB (echo 52428800 > /sys/kernel/kexec_crash_size), /proc/iomem still shows 256MB reserved: af000000-beffffff : Crash kernel Instead, it should show 50MB: af000000-b21fffff : Crash kernel Further shrinking crashkernel to 40MB causes a kernel crash with the following trace (x86): BUG: kernel NULL pointer dereference, address: 0000000000000038 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI <snip...> Call Trace: <TASK> ? __die_body.cold+0x19/0x27 ? page_fault_oops+0x15a/0x2f0 ? search_module_extables+0x19/0x60 ? search_bpf_extables+0x5f/0x80 ? exc_page_fault+0x7e/0x180 ? asm_exc_page_fault+0x26/0x30 ? __release_resource+0xd/0xb0 release_resource+0x26/0x40 __crash_shrink_memory+0xe5/0x110 crash_shrink_memory+0x12a/0x190 kexec_crash_size_store+0x41/0x80 kernfs_fop_write_iter+0x141/0x1f0 vfs_write+0x294/0x460 ksys_write+0x6d/0xf0 <snip...> This happens because __crash_shrink_memory()/kernel/crash_core.c incorrectly updates the crashk_res resource object even when crashk_low_res should be updated. Fix this by ensuring the correct crashkernel resource object is updated when shrinking crashkernel memory.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 16c6006af4d4e70ecef93977a5314409d931020b , < f01f9c348d76d40bf104a94449e3ce4057fdefee (git)
Affected: 16c6006af4d4e70ecef93977a5314409d931020b , < f89c5e7077f63e45e8ba5a77b7cf0803130367e6 (git)
Affected: 16c6006af4d4e70ecef93977a5314409d931020b , < a2bd247f8c6c5ac3f0ba823a2fffd77bb9cdf618 (git)
Affected: 16c6006af4d4e70ecef93977a5314409d931020b , < 00fbff75c5acb4755f06f08bd1071879c63940c5 (git)
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Linux Linux Affected: 6.5
Unaffected: 0 , < 6.5 (semver)
Unaffected: 6.6.118 , ≤ 6.6.* (semver)
Unaffected: 6.12.59 , ≤ 6.12.* (semver)
Unaffected: 6.17.9 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrash: fix crashkernel resource shrink\n\nWhen crashkernel is configured with a high reservation, shrinking its\nvalue below the low crashkernel reservation causes two issues:\n\n1. Invalid crashkernel resource objects\n2. Kernel crash if crashkernel shrinking is done twice\n\nFor example, with crashkernel=200M,high, the kernel reserves 200MB of high\nmemory and some default low memory (say 256MB).  The reservation appears\nas:\n\ncat /proc/iomem | grep -i crash\naf000000-beffffff : Crash kernel\n433000000-43f7fffff : Crash kernel\n\nIf crashkernel is then shrunk to 50MB (echo 52428800 \u003e\n/sys/kernel/kexec_crash_size), /proc/iomem still shows 256MB reserved:\naf000000-beffffff : Crash kernel\n\nInstead, it should show 50MB:\naf000000-b21fffff : Crash kernel\n\nFurther shrinking crashkernel to 40MB causes a kernel crash with the\nfollowing trace (x86):\n\nBUG: kernel NULL pointer dereference, address: 0000000000000038\nPGD 0 P4D 0\nOops: 0000 [#1] PREEMPT SMP NOPTI\n\u003csnip...\u003e\nCall Trace: \u003cTASK\u003e\n? __die_body.cold+0x19/0x27\n? page_fault_oops+0x15a/0x2f0\n? search_module_extables+0x19/0x60\n? search_bpf_extables+0x5f/0x80\n? exc_page_fault+0x7e/0x180\n? asm_exc_page_fault+0x26/0x30\n? __release_resource+0xd/0xb0\nrelease_resource+0x26/0x40\n__crash_shrink_memory+0xe5/0x110\ncrash_shrink_memory+0x12a/0x190\nkexec_crash_size_store+0x41/0x80\nkernfs_fop_write_iter+0x141/0x1f0\nvfs_write+0x294/0x460\nksys_write+0x6d/0xf0\n\u003csnip...\u003e\n\nThis happens because __crash_shrink_memory()/kernel/crash_core.c\nincorrectly updates the crashk_res resource object even when\ncrashk_low_res should be updated.\n\nFix this by ensuring the correct crashkernel resource object is updated\nwhen shrinking crashkernel memory."
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        "dateUpdated": "2026-05-11T21:48:33.671Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "url": "https://git.kernel.org/stable/c/00fbff75c5acb4755f06f08bd1071879c63940c5"
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    "datePublished": "2025-12-16T13:48:26.998Z",
    "dateReserved": "2025-12-16T13:41:40.254Z",
    "dateUpdated": "2026-05-11T21:48:33.671Z",
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}


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