"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nRISC-V: KVM: Don't zero-out PMU snapshot area before freeing data\n\nWith the latest Linux-6.11-rc3, the below NULL pointer crash is observed\nwhen SBI PMU snapshot is enabled for the guest and the guest is forcefully\npowered-off.\n\n Unable to handle kernel NULL pointer dereference at virtual address 0000000000000508\n Oops [#1]\n Modules linked in: kvm\n CPU: 0 UID: 0 PID: 61 Comm: term-poll Not tainted 6.11.0-rc3-00018-g44d7178dd77a #3\n Hardware name: riscv-virtio,qemu (DT)\n epc : __kvm_write_guest_page+0x94/0xa6 [kvm]\n ra : __kvm_write_guest_page+0x54/0xa6 [kvm]\n epc : ffffffff01590e98 ra : ffffffff01590e58 sp : ffff8f80001f39b0\n gp : ffffffff81512a60 tp : ffffaf80024872c0 t0 : ffffaf800247e000\n t1 : 00000000000007e0 t2 : 0000000000000000 s0 : ffff8f80001f39f0\n s1 : 00007fff89ac4000 a0 : ffffffff015dd7e8 a1 : 0000000000000086\n a2 : 0000000000000000 a3 : ffffaf8000000000 a4 : ffffaf80024882c0\n a5 : 0000000000000000 a6 : ffffaf800328d780 a7 : 00000000000001cc\n s2 : ffffaf800197bd00 s3 : 00000000000828c4 s4 : ffffaf800248c000\n s5 : ffffaf800247d000 s6 : 0000000000001000 s7 : 0000000000001000\n s8 : 0000000000000000 s9 : 00007fff861fd500 s10: 0000000000000001\n s11: 0000000000800000 t3 : 00000000000004d3 t4 : 00000000000004d3\n t5 : ffffffff814126e0 t6 : ffffffff81412700\n status: 0000000200000120 badaddr: 0000000000000508 cause: 000000000000000d\n [<ffffffff01590e98>] __kvm_write_guest_page+0x94/0xa6 [kvm]\n [<ffffffff015943a6>] kvm_vcpu_write_guest+0x56/0x90 [kvm]\n [<ffffffff015a175c>] kvm_pmu_clear_snapshot_area+0x42/0x7e [kvm]\n [<ffffffff015a1972>] kvm_riscv_vcpu_pmu_deinit.part.0+0xe0/0x14e [kvm]\n [<ffffffff015a2ad0>] kvm_riscv_vcpu_pmu_deinit+0x1a/0x24 [kvm]\n [<ffffffff0159b344>] kvm_arch_vcpu_destroy+0x28/0x4c [kvm]\n [<ffffffff0158e420>] kvm_destroy_vcpus+0x5a/0xda [kvm]\n [<ffffffff0159930c>] kvm_arch_destroy_vm+0x14/0x28 [kvm]\n [<ffffffff01593260>] kvm_destroy_vm+0x168/0x2a0 [kvm]\n [<ffffffff015933d4>] kvm_put_kvm+0x3c/0x58 [kvm]\n [<ffffffff01593412>] kvm_vm_release+0x22/0x2e [kvm]\n\nClearly, the kvm_vcpu_write_guest() function is crashing because it is\nbeing called from kvm_pmu_clear_snapshot_area() upon guest tear down.\n\nTo address the above issue, simplify the kvm_pmu_clear_snapshot_area() to\nnot zero-out PMU snapshot area from kvm_pmu_clear_snapshot_area() because\nthe guest is anyway being tore down.\n\nThe kvm_pmu_clear_snapshot_area() is also called when guest changes\nPMU snapshot area of a VCPU but even in this case the previous PMU\nsnaphsot area must not be zeroed-out because the guest might have\nreclaimed the pervious PMU snapshot area for some other purpose."
"value":"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: RISC-V: KVM: No ponga a cero el \u00e1rea de instant\u00e1neas de PMU antes de liberar los datos. Con la \u00faltima versi\u00f3n Linux-6.11-rc3, se observa el siguiente bloqueo del puntero NULL cuando la instant\u00e1nea de SBI PMU est\u00e1 habilitada para el invitado y el invitado se apaga a la fuerza. No se puede manejar la desreferencia del puntero NULL del n\u00facleo en la direcci\u00f3n virtual 0000000000000508 Ups [#1] M\u00f3dulos vinculados: kvm CPU: 0 UID: 0 PID: 61 Comm: term-poll No contaminado 6.11.0-rc3-00018-g44d7178dd77a #3 Nombre del hardware: riscv-virtio,qemu (DT) epc : __kvm_write_guest_page+0x94/0xa6 [kvm] ra : __kvm_write_guest_page+0x54/0xa6 [kvm] epc : ffffffff01590e98 ra : ffffffff01590e58 sp : ffff8f80001f39b0 gp : ffffffff81512a60 tp: ffffaf80024872c0 t0: ffffaf800247e000 t1: 00000000000007e0 t2: 00000000000000000 s0: ffff8f80001f39f0 s1: 00007fff89ac40 00 a0: ffffffff015dd7e8 a1: 0000000000000086 a2: 0000000000000000 a3: ffffaf8000000000 a4: ffffaf80024882c0 a5: 0000000000000000 a6: ffffaf800328d780 a7: 00000000000001cc s2: ffffaf800197bd00 s3: 00000000000828c4 s4: ffffaf800248c000 s5: 7d000 s6: 0000000000001000 s7: 0000000000001000 s8: 0000000000000000 s9: 00007fff861fd500 s10: 0000000000000001 s11: 0000000000800000 t3 : 00000000000004d3 t4 : 000000000000004d3 t5 : ffffffff814126e0 t6 : ffffffff81412700 estado: 0000000200000120 direcci\u00f3n incorrecta: 0000000000000508 causa: 000000000000000d [] __kvm_write_guest_page+0x94/0xa6 [kvm] [] kvm_vcpu_write_guest+0x56/0x90 [kvm] [] kvm_pmu_clear_snapshot_area+0x42/0x7e [kvm] [] kvm_riscv_vcpu_pmu_deinit.part.0+0xe0/0x14e [kvm] [] kvm_riscv_vcpu_pmu_deinit+0x1a/0x24 [kvm] [] kvm_arch_vcpu_destroy+0x28/0x4c [kvm] [] kvm_destroy_vcpus+0x5a/0xda [kvm] [] kvm_arch_destroy_vm+0x14/0x28 [kvm] [] kvm_destroy_vm+0x168/0x2a0 [kvm] [] kvm_put_kvm+0x3c/0x58 [kvm] [] kvm_vm_release+0x22/0x2e [kvm] Claramente, la funci\u00f3n kvm_vcpu_write_guest() falla porque se la llama desde kvm_pmu_clear_snapshot_area() al desmantelar el invitado. Para solucionar el problema anterior, simplifique kvm_pmu_clear_snapshot_area() para que no ponga a cero el \u00e1rea de instant\u00e1neas de PMU de kvm_pmu_clear_snapshot_area() porque, de todos modos, el invitado se est\u00e1 desmantelando. Tambi\u00e9n se llama a kvm_pmu_clear_snapshot_area() cuando el invitado cambia el \u00e1rea de instant\u00e1neas de PMU de una VCPU, pero incluso en este caso, el \u00e1rea de instant\u00e1neas de PMU anterior no debe ponerse a cero porque el invitado podr\u00eda haber recuperado el \u00e1rea de instant\u00e1neas de PMU anterior para alg\u00fan otro prop\u00f3sito."
