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CVE-2022-49851: riscv: fix reserved memory setup

In the Linux kernel, the following vulnerability has been resolved: riscv: fix reserved memory setup Currently, RISC-V sets up reserved memory using the "early" copy of the device tree. As a result, when trying to get a reserved memory region using of_reserved_mem_lookup(), the pointer to reserved memory regions is using the early, pre-virtual-memory address which causes a kernel panic when trying to use the buffer's name: Unable to handle kernel paging request at virtual address 00000000401c31ac Oops [#1] Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 6.0.0-rc1-00001-g0d9d6953d834 #1 Hardware name: Microchip PolarFire-SoC Icicle Kit (DT) epc : string+0x4a/0xea ra : vsnprintf+0x1e4/0x336 epc : ffffffff80335ea0 ra : ffffffff80338936 sp : ffffffff81203be0 gp : ffffffff812e0a98 tp : ffffffff8120de40 t0 : 0000000000000000 t1 : ffffffff81203e28 t2 : 7265736572203a46 s0 : ffffffff81203c20 s1 : ffffffff81203e28 a0 : ffffffff81203d22 a1 : 0000000000000000 a2 : ffffffff81203d08 a3 : 0000000081203d21 a4 : ffffffffffffffff a5 : 00000000401c31ac a6 : ffff0a00ffffff04 a7 : ffffffffffffffff s2 : ffffffff81203d08 s3 : ffffffff81203d00 s4 : 0000000000000008 s5 : ffffffff000000ff s6 : 0000000000ffffff s7 : 00000000ffffff00 s8 : ffffffff80d9821a s9 : ffffffff81203d22 s10: 0000000000000002 s11: ffffffff80d9821c t3 : ffffffff812f3617 t4 : ffffffff812f3617 t5 : ffffffff812f3618 t6 : ffffffff81203d08 status: 0000000200000100 badaddr: 00000000401c31ac cause: 000000000000000d [<ffffffff80338936>] vsnprintf+0x1e4/0x336 [<ffffffff80055ae2>] vprintk_store+0xf6/0x344 [<ffffffff80055d86>] vprintk_emit+0x56/0x192 [<ffffffff80055ed8>] vprintk_default+0x16/0x1e [<ffffffff800563d2>] vprintk+0x72/0x80 [<ffffffff806813b2>] _printk+0x36/0x50 [<ffffffff8068af48>] print_reserved_mem+0x1c/0x24 [<ffffffff808057ec>] paging_init+0x528/0x5bc [<ffffffff808031ae>] setup_arch+0xd0/0x592 [<ffffffff8080070e>] start_kernel+0x82/0x73c early_init_fdt_scan_reserved_mem() takes no arguments as it operates on initial_boot_params, which is populated by early_init_dt_verify(). On RISC-V, early_init_dt_verify() is called twice. Once, directly, in setup_arch() if CONFIG_BUILTIN_DTB is not enabled and once indirectly, very early in the boot process, by parse_dtb() when it calls early_init_dt_scan_nodes(). This first call uses dtb_early_va to set initial_boot_params, which is not usable later in the boot process when early_init_fdt_scan_reserved_mem() is called. On arm64 for example, the corresponding call to early_init_dt_scan_nodes() uses fixmap addresses and doesn't suffer the same fate. Move early_init_fdt_scan_reserved_mem() further along the boot sequence, after the direct call to early_init_dt_verify() in setup_arch() so that the names use the correct virtual memory addresses. The above supposed that CONFIG_BUILTIN_DTB was not set, but should work equally in the case where it is - unflatted_and_copy_device_tree() also updates initial_boot_params.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2022-49851 is a Linux kernel RISC-V boot-time bug. A reserved-memory device tree pointer can reference an address that is no longer valid, leading to a kernel panic while setting up memory. The main business impact is availability: affected RISC-V systems may fail during boot or early initialization.

Executive priority

Medium for organizations operating RISC-V Linux devices, especially embedded or appliance fleets where failed boots create outages. Low relevance for environments without RISC-V Linux exposure. No active exploitation is documented in the supplied sources.

Technical view

RISC-V used the early device tree copy for reserved memory setup. Later, of_reserved_mem_lookup() could retain pre-virtual-memory pointers, and printing a reserved-memory name could fault. The fix moves early_init_fdt_scan_reserved_mem() later in setup_arch(), after initial_boot_params is updated to usable virtual addresses.

Likely exposure

Exposure appears limited to Linux on RISC-V systems using affected kernel versions or commits and reserved-memory device tree regions. The source lists Linux kernel 5.4, 5.10.155, 5.15.79, 6.0.9, and 6.1 entries, but exact downstream distribution status requires vendor confirmation.

Exploitation context

The source bundle shows KEV is false and provides no evidence of active exploitation. This is described as a kernel panic during boot-time reserved-memory setup, not as a remote attack path. Treat it primarily as an availability and platform reliability issue for affected RISC-V deployments.

Researcher notes

The evidence is kernel-maintainer text and stable commit references. No CVSS, CWE, or exploitability details are supplied. Validation should focus on code lineage, architecture configuration, device tree reserved-memory usage, and whether downstream kernels include the stable fixes.

Mitigation direction

  • Update to a vendor or distribution kernel containing the referenced stable fixes.
  • Check RISC-V board and distribution advisories for backported kernel packages.
  • Prioritize systems that rely on reserved-memory device tree regions.
  • Avoid assuming non-RISC-V Linux systems are affected from this source alone.

Validation and detection

  • Inventory Linux kernels running on RISC-V hardware or images.
  • Compare kernel source or changelogs against the referenced stable commits.
  • Boot-test representative affected hardware after updating the kernel.
  • Review boot logs for reserved-memory or early paging panic traces.
Prepared
Confidence
medium
Sources
6

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

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

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
LinuxLinux922b0375fc93fb1a20c5617e37c389c26bbccb70, 922b0375fc93fb1a20c5617e37c389c26bbccb70, 922b0375fc93fb1a20c5617e37c389c26bbccb70, 922b0375fc93fb1a20c5617e37c389c26bbccb70, f18ed5bee7bb8a0e99e1c7e7d45e0e51d3497248unaffected
LinuxLinux5.4, 0, 5.10.155, 5.15.79, 6.0.9, 6.1affected
Weakness

CWE details

No CWE listed

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