CVE-2022-49353

Summary

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

powerpc/papr_scm: don't requests stats with '0' sized stats buffer

Sachin reported [1] that on a POWER-10 lpar he is seeing a kernel panic being reported with vPMEM when papr_scm probe is being called. The panic is of the form below and is observed only with following option disabled(profile) for the said LPAR 'Enable Performance Information Collection' in the HMC:

Kernel attempted to write user page (1c) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on write at 0x0000001c Faulting instruction address: 0xc008000001b90844 Oops: Kernel access of bad area, sig: 11 [#1] <snip> NIP [c008000001b90844] drc_pmem_query_stats+0x5c/0x270 [papr_scm] LR [c008000001b92794] papr_scm_probe+0x2ac/0x6ec [papr_scm] Call Trace: 0xc00000000941bca0 (unreliable) papr_scm_probe+0x2ac/0x6ec [papr_scm] platform_probe+0x98/0x150 really_probe+0xfc/0x510 __driver_probe_device+0x17c/0x230 <snip> —[ end trace 0000000000000000 ]— Kernel panic - not syncing: Fatal exception

On investigation looks like this panic was caused due to a 'stat_buffer' of size==0 being provided to drc_pmem_query_stats() to fetch all performance stats-ids of an NVDIMM. However drc_pmem_query_stats() shouldn't have been called since the vPMEM NVDIMM doesn't support and performance stat-id's. This was caused due to missing check for 'p->stat_buffer_len' at the beginning of papr_scm_pmu_check_events() which indicates that the NVDIMM doesn't support performance-stats.

Fix this by introducing the check for 'p->stat_buffer_len' at the beginning of papr_scm_pmu_check_events().

[1] https://lore.kernel.org/all/6B3A522A-6A5F-4CC9-B268-0C63AA6E07D3@linux.ibm.com

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxb073096df4dec70d0436321b7093bad27ae91f9e < e1295aab2ebcda1c1a9ed342baedc080e5c393e5affected
LinuxLinux0e0946e22f3665d27325d389ff45ade6e93f3678 < 07bf9431b1590d1cd7a8d62075d0b50b073f0495affected
LinuxLinux5.18.3 < 5.18.4affected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References