github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-03 12:03:54 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

KVM: x86/mmu: Harden TDP MMU iteration against root w/o shadow page

Browse Source 
Explicitly check that tdp_iter_start() is handed a valid shadow page
to harden KVM against bugs, e.g. if KVM calls into the TDP MMU with an
invalid or shadow MMU root (which would be a fatal KVM bug), the shadow
page pointer will be NULL.

Opportunistically stop the TDP MMU iteration instead of continuing on
with garbage if the incoming root is bogus.  Attempting to walk a garbage
root is more likely to caused major problems than doing nothing.

Cc: Yu Zhang <yu.c.zhang@linux.intel.com>
Link: https://lore.kernel.org/r/20230729005200.1057358-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2023-07-28 17:51:58 -07:00 committed by Paolo Bonzini
parent c30e000e69
commit 2c6d4c27b9
1 changed files with 6 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
arch/x86/kvm/mmu/tdp_iter.c
View File

@ -39,13 +39,14 @@ void tdp_iter_restart(struct tdp_iter *iter)
void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root,
int min_level, gfn_t next_last_level_gfn)
{
int root_level = root->role.level;
WARN_ON_ONCE(root_level < 1);
WARN_ON_ONCE(root_level > PT64_ROOT_MAX_LEVEL);
if (WARN_ON_ONCE(!root || (root->role.level < 1) ||
(root->role.level > PT64_ROOT_MAX_LEVEL))) {
iter->valid = false;
return;
}
iter->next_last_level_gfn = next_last_level_gfn;
iter->root_level = root_level;
iter->root_level = root->role.level;
iter->min_level = min_level;
iter->pt_path[iter->root_level - 1] = (tdp_ptep_t)root->spt;
iter->as_id = kvm_mmu_page_as_id(root);