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charset="UTF-8" X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Add a check on whether or not doing a user access is ok in KVM's APIs for accessing guest memory, *before* doing memslot lookup/validation, so that buggy KVM accesses to guest memory more likely to fail noisily. Because KVM installs dummy/empty memslots early in VM destruction, bugs in the VM teardown path will fail on the memslot checks without getting to the WARNs buried in kvm_copy_{to,from}_user() and friends. Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1058b864d427..d8b914b76f90 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3298,6 +3298,11 @@ static int next_segment(unsigned long len, int offset) return len; } +static bool kvm_is_guest_access_ok(struct kvm *kvm, int offset, int len, int size) +{ + return kvm_can_do_uaccess(kvm) && !WARN_ON_ONCE(offset + len > size); +} + /* Copy @len bytes from guest memory at '(@gfn * PAGE_SIZE) + @offset' to @data */ static int __kvm_read_guest_page(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, void *data, int offset, int len) @@ -3305,7 +3310,7 @@ static int __kvm_read_guest_page(struct kvm *kvm, struct kvm_memory_slot *slot, int r; unsigned long addr; - if (WARN_ON_ONCE(offset + len > PAGE_SIZE)) + if (!kvm_is_guest_access_ok(kvm, offset, len, PAGE_SIZE)) return -EFAULT; addr = gfn_to_hva_memslot_prot(slot, gfn, NULL); @@ -3381,7 +3386,7 @@ static int __kvm_read_guest_atomic(struct kvm *kvm, struct kvm_memory_slot *slot int r; unsigned long addr; - if (WARN_ON_ONCE(offset + len > PAGE_SIZE)) + if (!kvm_is_guest_access_ok(kvm, offset, len, PAGE_SIZE)) return -EFAULT; addr = gfn_to_hva_memslot_prot(slot, gfn, NULL); @@ -3414,7 +3419,7 @@ static int __kvm_write_guest_page(struct kvm *kvm, int r; unsigned long addr; - if (WARN_ON_ONCE(offset + len > PAGE_SIZE)) + if (!kvm_is_guest_access_ok(kvm, offset, len, PAGE_SIZE)) return -EFAULT; addr = gfn_to_hva_memslot(memslot, gfn); @@ -3544,7 +3549,7 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, int r; gpa_t gpa = ghc->gpa + offset; - if (WARN_ON_ONCE(len + offset > ghc->len)) + if (!kvm_is_guest_access_ok(kvm, offset, len, ghc->len)) return -EINVAL; if (slots->generation != ghc->generation) { @@ -3582,7 +3587,7 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, int r; gpa_t gpa = ghc->gpa + offset; - if (WARN_ON_ONCE(len + offset > ghc->len)) + if (!kvm_is_guest_access_ok(kvm, offset, len, ghc->len)) return -EINVAL; if (slots->generation != ghc->generation) { -- 2.56.0.307.g5fe7bd680c-goog