Description
In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel: Fix segfault with PEBS-via-PT with sample_freq Currently, using PEBS-via-PT with a sample frequency instead of a sample period, causes a segfault. For example: BUG: kernel NULL pointer dereference, address: 0000000000000195 <NMI> ? __die_body.cold+0x19/0x27 ? page_fault_oops+0xca/0x290 ? exc_page_fault+0x7e/0x1b0 ? asm_exc_page_fault+0x26/0x30 ? intel_pmu_pebs_event_update_no_drain+0x40/0x60 ? intel_pmu_pebs_event_update_no_drain+0x32/0x60 intel_pmu_drain_pebs_icl+0x333/0x350 handle_pmi_common+0x272/0x3c0 intel_pmu_handle_irq+0x10a/0x2e0 perf_event_nmi_handler+0x2a/0x50 That happens because intel_pmu_pebs_event_update_no_drain() assumes all the pebs_enabled bits represent counter indexes, which is not always the case. In this particular case, bits 60 and 61 are set for PEBS-via-PT purposes. The behaviour of PEBS-via-PT with sample frequency is questionable because although a PMI is generated (PEBS_PMI_AFTER_EACH_RECORD), the period is not adjusted anyway. Putting that aside, fix intel_pmu_pebs_event_update_no_drain() by passing the mask of counter bits instead of 'size'. Note, prior to the Fixes commit, 'size' would be limited to the maximum counter index, so the issue was not hit.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
722e42e45c2f1c6d1adec7813651dba5139f52f4 to < ca51db23166767a8445deb8331c9b8d5205d9287affected722e42e45c2f1c6d1adec7813651dba5139f52f4 to < 0b1874a5b1173fbcb2185ab828f4c33d067e551eaffected722e42e45c2f1c6d1adec7813651dba5139f52f4 to < 99bcd91fabada0dbb1d5f0de44532d8008db93c6affecteda9d6d466bcf0621a872e1052bc40e4c6f0541b8daffected6.10.5 to < 6.11affected
Linux Linux
Default version status: affected
6.11affected0 to < 6.11unaffected6.12.31 to ≤ 6.12.*unaffected6.14.9 to ≤ 6.14.*unaffected6.15 to ≤ *unaffected