CyberSecBulletin
CVE-2022-50315NVD status: Modified

Linux: Improper Validation of Array Index

Published Updated By the CyberSecBulletin desk

CVE-2022-50315 is a high-severity improper validation of array index vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions f70bd4339cb68bc7e206af4c922bc0d249244403, da2ea4a961d9f89ed248734e7032350c260dc3a3, 67a00c299c5c143817c948fbc7de1a2fa1af38fb as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.17% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to f70bd4339cb68bc7e206af4c922bc0d249244403 or da2ea4a961d9f89ed248734e7032350c260dc3a3 or 67a00c299c5c143817c948fbc7de1a2fa1af38fb or 383b7c50f5445ff8dbbf03080905648d6980c39d, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.9.332 or 4.14.298 or 4.19.264 or 5.4.221, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, f70bd4339cb68bc7e206af4c922bc0d249244403; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, da2ea4a961d9f89ed248734e7032350c260dc3a3; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, 67a00c299c5c143817c948fbc7de1a2fa1af38fb; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, 383b7c50f5445ff8dbbf03080905648d6980c39d; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, 303d0f761431d848dd8d7ff9fd9b8c101879cabe; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, 8fbe13de1cc7cef2564be3cbf60400b33eee023b; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, d6314d5f68764550c84d732ce901ddd3ac6b415f; 18f7ba4c2f4be6b37d925931f04d6cc28d88d1ee up to, but not including, 1e41e693f458eef2d5728207dbd327cd3b16580a; and 1 more rangesf70bd4339cb68bc7e206af4c922bc0d249244403, da2ea4a961d9f89ed248734e7032350c260dc3a3, 67a00c299c5c143817c948fbc7de1a2fa1af38fb, 383b7c50f5445ff8dbbf03080905648d6980c39d, 303d0f761431d848dd8d7ff9fd9b8c101879cabe, 8fbe13de1cc7cef2564be3cbf60400b33eee023b
LinuxLinux Kernelbefore 4.9.332; 4.10 up to, but not including, 4.14.298; 4.15 up to, but not including, 4.19.264; 4.20 up to, but not including, 5.4.221; 5.5 up to, but not including, 5.10.152; 5.11 up to, but not including, 5.15.76; 5.16 up to, but not including, 6.0.6; 6.14.9.332, 4.14.298, 4.19.264, 5.4.221, 5.10.152, 5.15.76

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: ata: ahci: Match EM_MAX_SLOTS with SATA_PMP_MAX_PORTS UBSAN complains about array-index-out-of-bounds: [ 1.980703] kernel: UBSAN: array-index-out-of-bounds in /build/linux-9H675w/linux-5.15.0/drivers/ata/libahci.c:968:41 [ 1.980709] kernel: index 15 is out of range for type 'ahci_em_priv [8]' [ 1.980713] kernel: CPU: 0 PID: 209 Comm: scsi_eh_8 Not tainted 5.15.0-25-generic #25-Ubuntu [ 1.980716] kernel: Hardware name: System manufacturer System Product Name/P5Q3, BIOS 1102 06/11/2010 [ 1.980718] kernel: Call Trace: [ 1.980721] kernel: <TASK> [ 1.980723] kernel: show_stack+0x52/0x58 [ 1.980729] kernel: dump_stack_lvl+0x4a/0x5f [ 1.980734] kernel: dump_stack+0x10/0x12 [ 1.980736] kernel: ubsan_epilogue+0x9/0x45 [ 1.980739] kernel: __ubsan_handle_out_of_bounds.cold+0x44/0x49 [ 1.980742] kernel: ahci_qc_issue+0x166/0x170 [libahci] [ 1.980748] kernel: ata_qc_issue+0x135/0x240 [ 1.980752] kernel: ata_exec_internal_sg+0x2c4/0x580 [ 1.980754] kernel: ? vprintk_default+0x1d/0x20 [ 1.980759] kernel: ata_exec_internal+0x67/0xa0 [ 1.980762] kernel: sata_pmp_read+0x8d/0xc0 [ 1.980765] kernel: sata_pmp_read_gscr+0x3c/0x90 [ 1.980768] kernel: sata_pmp_attach+0x8b/0x310 [ 1.980771] kernel: ata_eh_revalidate_and_attach+0x28c/0x4b0 [ 1.980775] kernel: ata_eh_recover+0x6b6/0xb30 [ 1.980778] kernel: ? ahci_do_hardreset+0x180/0x180 [libahci] [ 1.980783] kernel: ? ahci_stop_engine+0xb0/0xb0 [libahci] [ 1.980787] kernel: ? ahci_do_softreset+0x290/0x290 [libahci] [ 1.980792] kernel: ? trace_event_raw_event_ata_eh_link_autopsy_qc+0xe0/0xe0 [ 1.980795] kernel: sata_pmp_eh_recover.isra.0+0x214/0x560 [ 1.980799] kernel: sata_pmp_error_handler+0x23/0x40 [ 1.980802] kernel: ahci_error_handler+0x43/0x80 [libahci] [ 1.980806] kernel: ata_scsi_port_error_handler+0x2b1/0x600 [ 1.980810] kernel: ata_scsi_error+0x9c/0xd0 [ 1.980813] kernel: scsi_error_handler+0xa1/0x180 [ 1.980817] kernel: ? scsi_unjam_host+0x1c0/0x1c0 [ 1.980820] kernel: kthread+0x12a/0x150 [ 1.980823] kernel: ? set_kthread_struct+0x50/0x50 [ 1.980826] kernel: ret_from_fork+0x22/0x30 [ 1.980831] kernel: </TASK> This happens because sata_pmp_init_links() initialize link->pmp up to SATA_PMP_MAX_PORTS while em_priv is declared as 8 elements array. I can't find the maximum Enclosure Management ports specified in AHCI spec v1.3.1, but "12.2.1 LED message type" states that "Port Multiplier Information" can utilize 4 bits, which implies it can support up to 16 ports. Hence, use SATA_PMP_MAX_PORTS as EM_MAX_SLOTS to resolve the issue. BugLink: https://bugs.launchpad.net/bugs/1970074

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Validation of Array Index

The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.

How developers prevent this class of flaw

  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, Ada allows the programmer to constrain the values of a variable and languages such as Java and Ruby will allow the programmer to handle exceptions when an out-of-bounds index is accessed.
  • Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND.

More Improper Validation of Array Index vulnerabilities (CWE-129)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Validation of Array Index vulnerabilities

Spotted an error? Tell us.