CVE-2021-4439 (GCVE-0-2021-4439)

Vulnerability from cvelistv5 – Published: 2024-06-20 12:07 – Updated: 2025-12-18 11:35
VLAI?
Title
isdn: cpai: check ctr->cnr to avoid array index out of bound
Summary
In the Linux kernel, the following vulnerability has been resolved: isdn: cpai: check ctr->cnr to avoid array index out of bound The cmtp_add_connection() would add a cmtp session to a controller and run a kernel thread to process cmtp. __module_get(THIS_MODULE); session->task = kthread_run(cmtp_session, session, "kcmtpd_ctr_%d", session->num); During this process, the kernel thread would call detach_capi_ctr() to detach a register controller. if the controller was not attached yet, detach_capi_ctr() would trigger an array-index-out-bounds bug. [ 46.866069][ T6479] UBSAN: array-index-out-of-bounds in drivers/isdn/capi/kcapi.c:483:21 [ 46.867196][ T6479] index -1 is out of range for type 'capi_ctr *[32]' [ 46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted 5.15.0-rc2+ #8 [ 46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 46.870107][ T6479] Call Trace: [ 46.870473][ T6479] dump_stack_lvl+0x57/0x7d [ 46.870974][ T6479] ubsan_epilogue+0x5/0x40 [ 46.871458][ T6479] __ubsan_handle_out_of_bounds.cold+0x43/0x48 [ 46.872135][ T6479] detach_capi_ctr+0x64/0xc0 [ 46.872639][ T6479] cmtp_session+0x5c8/0x5d0 [ 46.873131][ T6479] ? __init_waitqueue_head+0x60/0x60 [ 46.873712][ T6479] ? cmtp_add_msgpart+0x120/0x120 [ 46.874256][ T6479] kthread+0x147/0x170 [ 46.874709][ T6479] ? set_kthread_struct+0x40/0x40 [ 46.875248][ T6479] ret_from_fork+0x1f/0x30 [ 46.875773][ T6479]
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < e8b8de17e164c9f1b7777f1c6f99d05539000036 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 24219a977bfe3d658687e45615c70998acdbac5a (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 9b6b2db77bc3121fe435f1d4b56e34de443bec75 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7d91adc0ccb060ce564103315189466eb822cc6a (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 285e9210b1fab96a11c0be3ed5cea9dd48b6ac54 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7f221ccbee4ec662e2292d490a43ce6c314c4594 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < cc20226e218a2375d50dd9ac14fb4121b43375ff (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 1f3e2e97c003f80c4b087092b225c8787ff91e4d (git)
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    Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 4.4.290 , ≤ 4.4.* (semver)
Unaffected: 4.9.288 , ≤ 4.9.* (semver)
Unaffected: 4.14.253 , ≤ 4.14.* (semver)
Unaffected: 4.19.214 , ≤ 4.19.* (semver)
Unaffected: 5.4.156 , ≤ 5.4.* (semver)
Unaffected: 5.10.76 , ≤ 5.10.* (semver)
Unaffected: 5.14.15 , ≤ 5.14.* (semver)
Unaffected: 5.15 , ≤ * (original_commit_for_fix)
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\"4.14.*\"}, {\"status\": \"unaffected\", \"version\": \"4.19.214\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"4.19.*\"}, {\"status\": \"unaffected\", \"version\": \"5.4.156\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.4.*\"}, {\"status\": \"unaffected\", \"version\": \"5.10.76\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.14.15\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.14.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"drivers/isdn/capi/kcapi.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/e8b8de17e164c9f1b7777f1c6f99d05539000036\"}, {\"url\": \"https://git.kernel.org/stable/c/24219a977bfe3d658687e45615c70998acdbac5a\"}, {\"url\": \"https://git.kernel.org/stable/c/9b6b2db77bc3121fe435f1d4b56e34de443bec75\"}, {\"url\": \"https://git.kernel.org/stable/c/7d91adc0ccb060ce564103315189466eb822cc6a\"}, {\"url\": \"https://git.kernel.org/stable/c/285e9210b1fab96a11c0be3ed5cea9dd48b6ac54\"}, {\"url\": \"https://git.kernel.org/stable/c/7f221ccbee4ec662e2292d490a43ce6c314c4594\"}, {\"url\": \"https://git.kernel.org/stable/c/cc20226e218a2375d50dd9ac14fb4121b43375ff\"}, {\"url\": \"https://git.kernel.org/stable/c/1f3e2e97c003f80c4b087092b225c8787ff91e4d\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nisdn: cpai: check ctr-\u003ecnr to avoid array index out of bound\\n\\nThe cmtp_add_connection() would add a cmtp session to a controller\\nand run a kernel thread to process cmtp.\\n\\n\\t__module_get(THIS_MODULE);\\n\\tsession-\u003etask = kthread_run(cmtp_session, session, \\\"kcmtpd_ctr_%d\\\",\\n\\t\\t\\t\\t\\t\\t\\t\\tsession-\u003enum);\\n\\nDuring this process, the kernel thread would call detach_capi_ctr()\\nto detach a register controller. if the controller\\nwas not attached yet, detach_capi_ctr() would\\ntrigger an array-index-out-bounds bug.\\n\\n[   46.866069][ T6479] UBSAN: array-index-out-of-bounds in\\ndrivers/isdn/capi/kcapi.c:483:21\\n[   46.867196][ T6479] index -1 is out of range for type \u0027capi_ctr *[32]\u0027\\n[   46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted\\n5.15.0-rc2+ #8\\n[   46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX,\\n1996), BIOS 1.14.0-2 04/01/2014\\n[   46.870107][ T6479] Call Trace:\\n[   46.870473][ T6479]  dump_stack_lvl+0x57/0x7d\\n[   46.870974][ T6479]  ubsan_epilogue+0x5/0x40\\n[   46.871458][ T6479]  __ubsan_handle_out_of_bounds.cold+0x43/0x48\\n[   46.872135][ T6479]  detach_capi_ctr+0x64/0xc0\\n[   46.872639][ T6479]  cmtp_session+0x5c8/0x5d0\\n[   46.873131][ T6479]  ? __init_waitqueue_head+0x60/0x60\\n[   46.873712][ T6479]  ? cmtp_add_msgpart+0x120/0x120\\n[   46.874256][ T6479]  kthread+0x147/0x170\\n[   46.874709][ T6479]  ? set_kthread_struct+0x40/0x40\\n[   46.875248][ T6479]  ret_from_fork+0x1f/0x30\\n[   46.875773][ T6479]\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"4.4.290\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"4.9.288\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"4.14.253\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"4.19.214\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.4.156\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.76\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.14.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2025-12-10T07:09:01.263Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-4439\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-12-10T07:09:01.263Z\", \"dateReserved\": \"2024-06-20T12:07:18.155Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-06-20T12:07:57.944Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Sightings

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  • 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.