{"id":"DEBIAN-CVE-2022-49214","details":"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-\u003edsisr) 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\u003e 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\u003e 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\u003e 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\u003e 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]","modified":"2026-09-01T16:05:30.204552238Z","published":"2025-02-26T07:00:58.490Z","upstream":["CVE-2022-49214"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2022-49214"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.17.3-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49214.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.17.3-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49214.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.17.3-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49214.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}