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

Vulnerability from cvelistv5 – Published: 2025-12-16 13:48 – Updated: 2025-12-16 13:48
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": "2025-12-16T13:48:26.998Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/00fbff75c5acb4755f06f08bd1071879c63940c5"
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      ],
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    "datePublished": "2025-12-16T13:48:26.998Z",
    "dateReserved": "2025-12-16T13:41:40.254Z",
    "dateUpdated": "2025-12-16T13:48:26.998Z",
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}


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