In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
KVM: SEV: Allocate full pages for {DE,EN}CRYPT ops on SNP-enabled hosts<\/p>\n
When {de,en}crypting memory of an SEV or SEV-ES guest on an SNP-enabled
\nhost via a temporary buffer, allocate a full 4KiB page for the buffer to
\nensure the page containing the buffer is wholly owned by KVM, i.e. won’t
\nbe concurrently allocated and accessed by other kernel code while KVM is
\nusing the buffer to {de,en}crypt memory. On SNP-enabled platforms, when
\nsending SEV\/SEV-ES commands that trigger firmware writes to memory, the
\nto-be-written page(s) must be (temporarily) assigned to Firmware (as
\nrequired by the SNP architecture, to guard against using such commands as
\ngadgets to attack SNP guests). See snp_map_cmd_buf_desc() and friends.<\/p>\n
Unfortunately, transferring ownership of a page to Firmware makes the page
\ninaccessible to software, and thus writes generate RMP #PF violations. If
\nKVM uses a sub-page allocation for its temporary buffer, some other actor
\nin the kernel can allocate and use the other portions of the page, and thus
\ntrigger unexpected (and seemingly spurious) RMP #PF violations due to
\nsoftware attempting to access a Firmware-owned page.<\/p>\n
BUG: unable to handle page fault for address: ffff906ae30f0300
\n #PF: supervisor write access in kernel mode
\n #PF: error_code(0x80000003) – RMP violation
\n PGD 6b1b80d067 P4D 6b1b80d067 PUD 100231e2063 PMD 10055a88063 PTE 80000100630f0163
\n SEV-SNP: PFN 0x100630f0 unassigned, dumping non-zero entries in 2M PFN region: [0x10063000 – 0x10063200]
\n Oops: Oops: 0003 [#1] SMP
\n CPU: 70 UID: 0 PID: 10658 Comm: svw_WaiterThrea Tainted: G U W O 7.1.0-smp–c22293789940-seanjc-next #1 PREEMPTLAZY
\n Tainted: [U]=USER, [W]=WARN, [O]=OOT_MODULE
\n Hardware name: Google, Inc. Arcadia_IT_80\/Arcadia_IT_80, BIOS 34.86.0-102 01\/25\/2026
\n RIP: 0010:memset+0xf\/0x20
\n Call Trace:<\/p>\n
__kvmalloc_node_noprof+0x2a4\/0x710
\n do_getxattr+0x4e\/0x130
\n path_getxattrat+0x125\/0x1b0
\n do_syscall_64+0x10a\/0x480
\n entry_SYSCALL_64_after_hwframe+0x4b\/0x53
\n RIP: 0033:0x7f3a22cb6daa<\/p>\n
Modules linked in: kvm_amd kvm irqbypass vfat fat ccp k10temp sha3 libsha3 i2c_piix4 gq(O) cdc_acm xhci_pci xhci_hcd
\n gsmi: Log Shutdown Reason 0x03
\n CR2: ffff906ae30f0300
\n —[ end trace 0000000000000000 ]—
\n RIP: 0010:memset+0xf\/0x20
\n Kernel panic – not syncing: Fatal exception
\n Kernel Offset: 0x39e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
\n gsmi: Log Shutdown Reason 0x02<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
KVM: SEV: Allocate full pages for {DE,EN}CRYPT ops on SNP-enabled hosts<\/p>\n
When {de,en}crypting memory of an SEV or SEV-ES guest on a<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-17357","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/17357","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=17357"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17357"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17357"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}