CVE-2026-64235 (GCVE-0-2026-64235)

Vulnerability from cvelistv5 – Published: 2026-07-24 15:27 – Updated: 2026-07-27 04:59
VLAI
Title
x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines With CONFIG_CALL_DEPTH_TRACKING enabled on an x86 retbleed-affected platform (eg: Skylake), with retbleed=stuff, registering a dynamic ftrace trampoline crashes on the first call into the traced function: BUG: unable to handle page fault for address: ffff88817ae18880 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 4b53067 P4D 4b53067 PUD 0 Oops: Oops: 0002 [#1] SMP PTI CPU: 3 UID: 0 PID: 187 Comm: usleep Not tainted 7.0.10 #243 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17.0-2-2 04/01/2014 Code: 24 78 00 00 00 00 48 89 ea 48 89 54 24 20 48 8b b4 24 b8 00 00 00 48 8b bc 24 b0 00 00 00 48 89 bc 24 80 00 00 00 48 83 ef 05 <65> 48 c1 3d 1f a8 b6 02 05 48 8b 15 f6 00 00 00 4c 89 3c 24 4c 89 Call Trace: <TASK> ? find_held_lock ? exc_page_fault ? lock_release ? __x64_sys_clock_nanosleep ? lockdep_hardirqs_on_prepare ? trace_hardirqs_on __x64_sys_clock_nanosleep do_syscall_64 ? exc_page_fault ? call_depth_return_thunk entry_SYSCALL_64_after_hwframe ... Kernel panic - not syncing: Fatal exception This small reproducer allows to easily trigger the crash: # echo 'p __x64_sys_clock_nanosleep' > /sys/kernel/tracing/kprobe_events # echo 1 > /sys/kernel/tracing/events/kprobes/p___x64_sys_clock_nanosleep_0/enable # usleep 1 Monitoring the crash under GDB points to the exact instruction in charge of incrementing the call depth: sarq $5, %gs:__x86_call_depth(%rip) This instruction matches the one inserted by the ftrace_regs_caller from ftrace_64.S. This emitted code was likely working fine until the introduction of 59bec00ace28 ("x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR()"): it has made the call depth accounting addressing relative to $rip, instead of being based on an absolute address. As this code exact location depends on where the trampoline lives in memory, the corresponding displacement needs to be adjusted at runtime to actually correctly find the per-cpu __x86_call_depth value, otherwise the targeted address is wrong, leading to the page fault seen above. Fix the %rip-relative displacement of the copied CALL_DEPTH_ACCOUNT instruction (from ftrace_regs_caller) by calling text_poke_apply_relocation(), as it is done for example by the x86 BPF JIT compiler through x86_call_depth_emit_accounting(). This corrects both CALL_DEPTH_ACCOUNT slots, in ftrace_caller and ftrace_regs_caller. [ bp: Massage. ]
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 59bec00ace28d565ae0a68b23063ef3b961d82d5 , < 8093442a2d1d4b42b9340a86023ccb2afb30b93a (git)
Affected: 59bec00ace28d565ae0a68b23063ef3b961d82d5 , < d59cc66b702757e3c5a711e78a38583eac0c2738 (git)
Affected: 59bec00ace28d565ae0a68b23063ef3b961d82d5 , < 9edff632ca216169846f8a63a5a3dc467e239c7a (git)
Affected: 59bec00ace28d565ae0a68b23063ef3b961d82d5 , < a17dc12bfed8868e6a86f3b45c16065a70641acb (git)
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Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/kernel/ftrace.c"
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                  "versionStartIncluding": "6.9",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines\n\nWith CONFIG_CALL_DEPTH_TRACKING enabled on an x86 retbleed-affected platform\n(eg: Skylake), with retbleed=stuff, registering a dynamic ftrace trampoline\ncrashes on the first call into the traced function:\n\n  BUG: unable to handle page fault for address: ffff88817ae18880\n  #PF: supervisor write access in kernel mode\n  #PF: error_code(0x0002) - not-present page\n  PGD 4b53067 P4D 4b53067 PUD 0\n  Oops: Oops: 0002 [#1] SMP PTI\n  CPU: 3 UID: 0 PID: 187 Comm: usleep Not tainted 7.0.10 #243 PREEMPT(full)\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17.0-2-2 04/01/2014\n  Code: 24 78 00 00 00 00 48 89 ea 48 89 54 24 20 48 8b b4 24 b8 00 00 00 48 8b bc 24 b0 00 00 00 48 89 bc 24 80 00 00 00 48 83 ef 05 \u003c65\u003e 48 c1 3d 1f a8 b6 02 05 48 8b 15 f6 00 00 00 4c 89 3c 24 4c 89\n  Call Trace:\n   \u003cTASK\u003e\n   ? find_held_lock\n   ? exc_page_fault\n   ? lock_release\n   ? __x64_sys_clock_nanosleep\n   ? lockdep_hardirqs_on_prepare\n   ? trace_hardirqs_on\n   __x64_sys_clock_nanosleep\n   do_syscall_64\n   ? exc_page_fault\n   ? call_depth_return_thunk\n   entry_SYSCALL_64_after_hwframe\n  ...\n  Kernel panic - not syncing: Fatal exception\n\nThis small reproducer allows to easily trigger the crash:\n\n  # echo \u0027p __x64_sys_clock_nanosleep\u0027 \u003e /sys/kernel/tracing/kprobe_events\n  # echo 1 \u003e /sys/kernel/tracing/events/kprobes/p___x64_sys_clock_nanosleep_0/enable\n  # usleep 1\n\nMonitoring the crash under GDB points to the exact instruction in charge of\nincrementing the call depth:\n\n  sarq $5, %gs:__x86_call_depth(%rip)\n\nThis instruction matches the one inserted by the ftrace_regs_caller from\nftrace_64.S. This emitted code was likely working fine until the introduction\nof\n\n  59bec00ace28 (\"x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR()\"):\n\nit has made the call depth accounting addressing relative to $rip, instead of\nbeing based on an absolute address.\n\nAs this code exact location depends on where the trampoline lives in memory,\nthe corresponding displacement needs to be adjusted at runtime to actually\ncorrectly find the per-cpu __x86_call_depth value, otherwise the targeted\naddress is wrong, leading to the page fault seen above.\n\nFix the %rip-relative displacement of the copied CALL_DEPTH_ACCOUNT\ninstruction (from ftrace_regs_caller) by calling text_poke_apply_relocation(),\nas it is done for example by the x86 BPF JIT compiler through\nx86_call_depth_emit_accounting(). This corrects both CALL_DEPTH_ACCOUNT slots,\nin ftrace_caller and ftrace_regs_caller.\n\n  [ bp: Massage. ]"
        }
      ],
      "metrics": [
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            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
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      "providerMetadata": {
        "dateUpdated": "2026-07-27T04:59:05.504Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/d59cc66b702757e3c5a711e78a38583eac0c2738"
        },
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          "url": "https://git.kernel.org/stable/c/9edff632ca216169846f8a63a5a3dc467e239c7a"
        },
        {
          "url": "https://git.kernel.org/stable/c/a17dc12bfed8868e6a86f3b45c16065a70641acb"
        }
      ],
      "title": "x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64235",
    "datePublished": "2026-07-24T15:27:40.814Z",
    "dateReserved": "2026-07-19T15:36:31.771Z",
    "dateUpdated": "2026-07-27T04:59:05.504Z",
    "state": "PUBLISHED"
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      "date": "2026-07-31",
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This emitted code was likely working fine until the introduction\\nof\\n\\n  59bec00ace28 (\\\"x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR()\\\"):\\n\\nit has made the call depth accounting addressing relative to $rip, instead of\\nbeing based on an absolute address.\\n\\nAs this code exact location depends on where the trampoline lives in memory,\\nthe corresponding displacement needs to be adjusted at runtime to actually\\ncorrectly find the per-cpu __x86_call_depth value, otherwise the targeted\\naddress is wrong, leading to the page fault seen above.\\n\\nFix the %rip-relative displacement of the copied CALL_DEPTH_ACCOUNT\\ninstruction (from ftrace_regs_caller) by calling text_poke_apply_relocation(),\\nas it is done for example by the x86 BPF JIT compiler through\\nx86_call_depth_emit_accounting(). This corrects both CALL_DEPTH_ACCOUNT slots,\\nin ftrace_caller and ftrace_regs_caller.\\n\\n  [ bp: Massage. ]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"arch/x86/kernel/ftrace.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"59bec00ace28d565ae0a68b23063ef3b961d82d5\",\"lessThan\":\"8093442a2d1d4b42b9340a86023ccb2afb30b93a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"59bec00ace28d565ae0a68b23063ef3b961d82d5\",\"lessThan\":\"d59cc66b702757e3c5a711e78a38583eac0c2738\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"59bec00ace28d565ae0a68b23063ef3b961d82d5\",\"lessThan\":\"9edff632ca216169846f8a63a5a3dc467e239c7a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"59bec00ace28d565ae0a68b23063ef3b961d82d5\",\"lessThan\":\"a17dc12bfed8868e6a86f3b45c16065a70641acb\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"arch/x86/kernel/ftrace.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.9\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.9\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.93\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.35\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.12\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.2,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/8093442a2d1d4b42b9340a86023ccb2afb30b93a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9edff632ca216169846f8a63a5a3dc467e239c7a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a17dc12bfed8868e6a86f3b45c16065a70641acb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d59cc66b702757e3c5a711e78a38583eac0c2738\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-28T09:58:20+00:00",
      "cve": "CVE-2026-64235",
      "id": "CVE-2026-64235",
      "initial_release_date": "2026-07-24T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64235.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-30T16:32:31Z",
      "cve": "CVE-2026-64235",
      "id": "CVE-2026-64235",
      "initial_release_date": "2026-07-25T00:13:58Z",
      "product_status:known_affected": "29",
      "product_status:known_not_affected": "269",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64235",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64235.json",
      "version": "5"
    }
  }
}



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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

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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.


Detection rules are retrieved from Rulezet.