CyberSecBulletin
CVE-2024-57849NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-57849 is a high-severity use after 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 238e3af849dfdcb1faed544349f7025e533f9aab, 99192c735ed4bfdff0d215ec85c8a87a677cb898, 06a92f810df8037ca36157282ddcbefdcaf049b8 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 0.21% 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 238e3af849dfdcb1faed544349f7025e533f9aab or 99192c735ed4bfdff0d215ec85c8a87a677cb898 or 06a92f810df8037ca36157282ddcbefdcaf049b8 or b5be6a0bb639d165c8418d8dddd8f322587be8be, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.4.287 or 5.10.231 or 5.15.174 or 6.1.120, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxe3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, 238e3af849dfdcb1faed544349f7025e533f9aab; e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, 99192c735ed4bfdff0d215ec85c8a87a677cb898; e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, 06a92f810df8037ca36157282ddcbefdcaf049b8; e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, b5be6a0bb639d165c8418d8dddd8f322587be8be; e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, a69752f1e5de817941a2ea0609254f6f25acd274; e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, be54e6e0f93a39a9c00478d70d12956a5f3d5b9b; e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 up to, but not including, a0bd7dacbd51c632b8e2c0500b479af564afadf3; 4.8238e3af849dfdcb1faed544349f7025e533f9aab, 99192c735ed4bfdff0d215ec85c8a87a677cb898, 06a92f810df8037ca36157282ddcbefdcaf049b8, b5be6a0bb639d165c8418d8dddd8f322587be8be, a69752f1e5de817941a2ea0609254f6f25acd274, be54e6e0f93a39a9c00478d70d12956a5f3d5b9b
LinuxLinux Kernelbefore 5.4.287; 5.5 up to, but not including, 5.10.231; 5.11 up to, but not including, 5.15.174; 5.16 up to, but not including, 6.1.120; 6.2 up to, but not including, 6.6.66; 6.7 up to, but not including, 6.12.55.4.287, 5.10.231, 5.15.174, 6.1.120, 6.6.66, 6.12.5

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: s390/cpum_sf: Handle CPU hotplug remove during sampling CPU hotplug remove handling triggers the following function call sequence: CPUHP_AP_PERF_S390_SF_ONLINE --> s390_pmu_sf_offline_cpu() ... CPUHP_AP_PERF_ONLINE --> perf_event_exit_cpu() The s390 CPUMF sampling CPU hotplug handler invokes: s390_pmu_sf_offline_cpu() +--> cpusf_pmu_setup() +--> setup_pmc_cpu() +--> deallocate_buffers() This function de-allocates all sampling data buffers (SDBs) allocated for that CPU at event initialization. It also clears the PMU_F_RESERVED bit. The CPU is gone and can not be sampled. With the event still being active on the removed CPU, the CPU event hotplug support in kernel performance subsystem triggers the following function calls on the removed CPU: perf_event_exit_cpu() +--> perf_event_exit_cpu_context() +--> __perf_event_exit_context() +--> __perf_remove_from_context() +--> event_sched_out() +--> cpumsf_pmu_del() +--> cpumsf_pmu_stop() +--> hw_perf_event_update() to stop and remove the event. During removal of the event, the sampling device driver tries to read out the remaining samples from the sample data buffers (SDBs). But they have already been freed (and may have been re-assigned). This may lead to a use after free situation in which case the samples are most likely invalid. In the best case the memory has not been reassigned and still contains valid data. Remedy this situation and check if the CPU is still in reserved state (bit PMU_F_RESERVED set). In this case the SDBs have not been released an contain valid data. This is always the case when the event is removed (and no CPU hotplug off occured). If the PMU_F_RESERVED bit is not set, the SDB buffers are gone.

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

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

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 Use After Free vulnerabilities

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