CyberSecBulletin
CVE-2023-52851NVD status: Analyzed

Linux: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2023-52851 is a high-severity double free 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 437f033e30c897bb3723eac9e9003cd9f88d00a3, 4f4a7a7d1404297f2a92df0046f7e64dc5c52dd9, 6387f269d84e6e149499408c4d1fc805017729b2 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 0.24% 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 437f033e30c897bb3723eac9e9003cd9f88d00a3 or 4f4a7a7d1404297f2a92df0046f7e64dc5c52dd9 or 6387f269d84e6e149499408c4d1fc805017729b2 or 2ef422f063b74adcc4a4a9004b0a87bb55e0a836, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.63 or 6.5.12 or 6.6.2, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux04876c12c19e94bbbc94bb0446c7bc7cd75163de up to, but not including, 437f033e30c897bb3723eac9e9003cd9f88d00a3; 04876c12c19e94bbbc94bb0446c7bc7cd75163de up to, but not including, 4f4a7a7d1404297f2a92df0046f7e64dc5c52dd9; 04876c12c19e94bbbc94bb0446c7bc7cd75163de up to, but not including, 6387f269d84e6e149499408c4d1fc805017729b2; 04876c12c19e94bbbc94bb0446c7bc7cd75163de up to, but not including, 2ef422f063b74adcc4a4a9004b0a87bb55e0a836; 5.19437f033e30c897bb3723eac9e9003cd9f88d00a3, 4f4a7a7d1404297f2a92df0046f7e64dc5c52dd9, 6387f269d84e6e149499408c4d1fc805017729b2, 2ef422f063b74adcc4a4a9004b0a87bb55e0a836
LinuxLinux Kernel5.19 up to, but not including, 6.1.63; 6.2 up to, but not including, 6.5.12; 6.6 up to, but not including, 6.6.26.1.63, 6.5.12, 6.6.2

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.

Official description

In the Linux kernel, the following vulnerability has been resolved: IB/mlx5: Fix init stage error handling to avoid double free of same QP and UAF In the unlikely event that workqueue allocation fails and returns NULL in mlx5_mkey_cache_init(), delete the call to mlx5r_umr_resource_cleanup() (which frees the QP) in mlx5_ib_stage_post_ib_reg_umr_init(). This will avoid attempted double free of the same QP when __mlx5_ib_add() does its cleanup. Resolves a splat: Syzkaller reported a UAF in ib_destroy_qp_user workqueue: Failed to create a rescuer kthread for wq "mkey_cache": -EINTR infiniband mlx5_0: mlx5_mkey_cache_init:981:(pid 1642): failed to create work queue infiniband mlx5_0: mlx5_ib_stage_post_ib_reg_umr_init:4075:(pid 1642): mr cache init failed -12 ================================================================== BUG: KASAN: slab-use-after-free in ib_destroy_qp_user (drivers/infiniband/core/verbs.c:2073) Read of size 8 at addr ffff88810da310a8 by task repro_upstream/1642 Call Trace: <TASK> kasan_report (mm/kasan/report.c:590) ib_destroy_qp_user (drivers/infiniband/core/verbs.c:2073) mlx5r_umr_resource_cleanup (drivers/infiniband/hw/mlx5/umr.c:198) __mlx5_ib_add (drivers/infiniband/hw/mlx5/main.c:4178) mlx5r_probe (drivers/infiniband/hw/mlx5/main.c:4402) ... </TASK> Allocated by task 1642: __kmalloc (./include/linux/kasan.h:198 mm/slab_common.c:1026 mm/slab_common.c:1039) create_qp (./include/linux/slab.h:603 ./include/linux/slab.h:720 ./include/rdma/ib_verbs.h:2795 drivers/infiniband/core/verbs.c:1209) ib_create_qp_kernel (drivers/infiniband/core/verbs.c:1347) mlx5r_umr_resource_init (drivers/infiniband/hw/mlx5/umr.c:164) mlx5_ib_stage_post_ib_reg_umr_init (drivers/infiniband/hw/mlx5/main.c:4070) __mlx5_ib_add (drivers/infiniband/hw/mlx5/main.c:4168) mlx5r_probe (drivers/infiniband/hw/mlx5/main.c:4402) ... Freed by task 1642: __kmem_cache_free (mm/slub.c:1826 mm/slub.c:3809 mm/slub.c:3822) ib_destroy_qp_user (drivers/infiniband/core/verbs.c:2112) mlx5r_umr_resource_cleanup (drivers/infiniband/hw/mlx5/umr.c:198) mlx5_ib_stage_post_ib_reg_umr_init (drivers/infiniband/hw/mlx5/main.c:4076 drivers/infiniband/hw/mlx5/main.c:4065) __mlx5_ib_add (drivers/infiniband/hw/mlx5/main.c:4168) mlx5r_probe (drivers/infiniband/hw/mlx5/main.c:4402) ...

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

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

Timeline

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

References

Recent Double Free vulnerabilities

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