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Vulnerability · Published Jun 20, 2024 · Assigned by Linux

CVE-2021-4439isdn: cpai: check ctr->cnr to avoid array index out of bound

High 7.8

In plain English

A high-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)7.8High
Exploit odds (30 days)0.2%top 85.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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]

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux5.14.16-1DEBIAN-CVE-2021-4439
Debian:13linux5.14.16-1DEBIAN-CVE-2021-4439
Debian:14linux5.14.16-1DEBIAN-CVE-2021-4439
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2021-4439
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2021-4439
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2021-4439

Affected products (as reported)

VendorProductVersions
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before e8b8de17e164c9f1b7777f1c6f99d055390000361da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before 24219a977bfe3d658687e45615c70998acdbac5a1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before 9b6b2db77bc3121fe435f1d4b56e34de443bec751da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before 7d91adc0ccb060ce564103315189466eb822cc6a1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before 285e9210b1fab96a11c0be3ed5cea9dd48b6ac541da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before 7f221ccbee4ec662e2292d490a43ce6c314c45941da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before cc20226e218a2375d50dd9ac14fb4121b43375ff1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – before 1f3e2e97c003f80c4b087092b225c8787ff91e4d
Linux Linux 2.6.12

References