Homepage

NULL Pointer Dereference Affecting kernel-modules-core package, versions <0:5.14.0-284.11.1.el9_2

Severity

 Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.05% (16th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications

Snyk Learn

Learn about NULL Pointer Dereference vulnerabilities in an interactive lesson.

Start learning
  • Snyk IDSNYK-RHEL9-KERNELMODULESCORE-11932224
  • published16 Aug 2025
  • disclosed26 Feb 2025
Report a new vulnerability Found a mistake?

Introduced: 26 Feb 2025

CVE-2022-49214  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade RHEL:9 kernel-modules-core to version 0:5.14.0-284.11.1.el9_2 or higher.
This issue was patched in RHSA-2023:2458.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-modules-core package and not the kernel-modules-core package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

powerpc/64s: Don't use DSISR for SLB faults

Since commit 46ddcb3950a2 ("powerpc/mm: Show if a bad page fault on data is read or write.") we use page_fault_is_write(regs->dsisr) in __bad_page_fault() to determine if the fault is for a read or write, and change the message printed accordingly.

But SLB faults, aka Data Segment Interrupts, don't set DSISR (Data Storage Interrupt Status Register) to a useful value. All ISA versions from v2.03 through v3.1 specify that the Data Segment Interrupt sets DSISR "to an undefined value". As far as I can see there's no mention of SLB faults setting DSISR in any BookIV content either.

This manifests as accesses that should be a read being incorrectly reported as writes, for example, using the xmon "dump" command:

0:mon> d 0x5deadbeef0000000 5deadbeef0000000 [359526.415354][ C6] BUG: Unable to handle kernel data access on write at 0x5deadbeef0000000 [359526.415611][ C6] Faulting instruction address: 0xc00000000010a300 cpu 0x6: Vector: 380 (Data SLB Access) at [c00000000ffbf400] pc: c00000000010a300: mread+0x90/0x190

If we disassemble the PC, we see a load instruction:

0:mon> di c00000000010a300 c00000000010a300 89490000 lbz r10,0(r9)

We can also see in exceptions-64s.S that the data_access_slb block doesn't set IDSISR=1, which means it doesn't load DSISR into pt_regs. So the value we're using to determine if the fault is a read/write is some stale value in pt_regs from a previous page fault.

Rework the printing logic to separate the SLB fault case out, and only print read/write in the cases where we can determine it.

The result looks like eg:

0:mon> d 0x5deadbeef0000000 5deadbeef0000000 [ 721.779525][ C6] BUG: Unable to handle kernel data access at 0x5deadbeef0000000 [ 721.779697][ C6] Faulting instruction address: 0xc00000000014cbe0 cpu 0x6: Vector: 380 (Data SLB Access) at [c00000000ffbf390]

0:mon> d 0 0000000000000000 [ 742.793242][ C6] BUG: Kernel NULL pointer dereference at 0x00000000 [ 742.793316][ C6] Faulting instruction address: 0xc00000000014cbe0 cpu 0x6: Vector: 380 (Data SLB Access) at [c00000000ffbf390]

CVSS Base Scores

version 3.1