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CVE Record

CVE-2022-49393: misc: fastrpc: fix list iterator in fastrpc_req_mem_unmap_impl

In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: fix list iterator in fastrpc_req_mem_unmap_impl This is another instance of incorrect use of list iterator and checking it for NULL. The list iterator value 'map' will *always* be set and non-NULL by list_for_each_entry(), so it is incorrect to assume that the iterator value will be NULL if the list is empty (in this case, the check 'if (!map) {' will always be false and never exit as expected). To fix the bug, use a new variable 'iter' as the list iterator, while use the original variable 'map' as a dedicated pointer to point to the found element. Without this patch, Kernel crashes with below trace: Unable to handle kernel access to user memory outside uaccess routines at virtual address 0000ffff7fb03750 ... Call trace: fastrpc_map_create+0x70/0x290 [fastrpc] fastrpc_req_mem_map+0xf0/0x2dc [fastrpc] fastrpc_device_ioctl+0x138/0xc60 [fastrpc] __arm64_sys_ioctl+0xa8/0xec invoke_syscall+0x48/0x114 el0_svc_common.constprop.0+0xd4/0xfc do_el0_svc+0x28/0x90 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xa4/0x130 el0t_64_sync+0x18c/0x190 Code: 14000016 f94000a5 eb05029f 54000260 (b94018a6) ---[ end trace 0000000000000000 ]---

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A flaw in the Linux kernel FastRPC component can cause a kernel crash when memory mapping requests are handled incorrectly. The supplied CVSS score is 7.8 and describes potential confidentiality, integrity, and availability impact, although the published description specifically demonstrates a crash.

Executive priority

Treat this as a high-priority kernel remediation where FastRPC is present, especially on shared or locally accessible systems. It does not warrant an emergency internet-wide response based on the supplied evidence, because exploitation is local and no active exploitation is documented.

Technical view

The unmap implementation incorrectly expected a list iterator to become NULL when no matching entry existed. Because list_for_each_entry always assigns the iterator, execution could continue with an invalid pointer and trigger an out-of-bounds kernel memory access. The fix separates iteration from the pointer representing a found mapping.

Likely exposure

Exposure is limited to Linux systems using the affected FastRPC kernel component. The bundle identifies versions in the Linux 5.18 and 5.19 area, but its version boundaries are ambiguous. Confirm affected ranges against kernel or distribution guidance and determine whether FastRPC is enabled and reachable by local users.

Exploitation context

The CVSS vector describes a local, low-complexity attack requiring low privileges and no user interaction. The supplied sources show a kernel crash but provide no evidence of active exploitation, and the CVE is not listed as KEV. Broader confidentiality or integrity impact is represented by CVSS but not demonstrated in the description.

Researcher notes

The concrete failure is invalid kernel memory access caused by incorrect list-iterator handling. The trace is from an arm64 ioctl path, but the bundle does not establish that every architecture or FastRPC configuration is affected. Exact version boundaries and exploitability beyond denial of service require vendor-specific confirmation.

Mitigation direction

  • Apply a vendor-supported kernel update containing the cited FastRPC iterator fix.
  • If updating is delayed, consult the kernel or distribution vendor for supported mitigations.
  • Restrict untrusted local access where operationally feasible until affected systems are remediated.
  • Prioritize systems where FastRPC is enabled and accessible to local users.

Validation and detection

  • Inventory kernel versions and compare them with current vendor advisories for CVE-2022-49393.
  • Determine whether the FastRPC component is built, loaded, or otherwise available on each system.
  • Verify the installed kernel includes the applicable cited stable commit or vendor backport.
  • Run approved regression testing around FastRPC memory mapping and unmapping after updating.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2022-49393 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2022-49393Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux5c1b97c7d7b736e6439af4f43a65837bc72f56c1, 5c1b97c7d7b736e6439af4f43a65837bc72f56c1unaffected
LinuxLinux5.18, 0, 5.18.3, 5.19affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.