CVE-2022-49214: In the Linux kernel, the following vulnerability has been resolved: powerpc/64s: Don't use DSISR for SLB faults Since commit 46ddcb3950a2 ("powerpc/...

Description

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]

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.25%

15.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	>= 5.5, < 5.15.33
Linux	Linux Kernel	>= 5.16, < 5.16.19
Linux	Linux Kernel	>= 5.17, < 5.17.2

References

Timeline

Published: Feb 26, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2022-49214?

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]

How severe is CVE-2022-49214?

CVE-2022-49214 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2022-49214?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.