diff options
Diffstat (limited to 'main/xen/xsa104.patch')
| -rw-r--r-- | main/xen/xsa104.patch | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/main/xen/xsa104.patch b/main/xen/xsa104.patch new file mode 100644 index 0000000000..2c5b39ee9b --- /dev/null +++ b/main/xen/xsa104.patch @@ -0,0 +1,44 @@ +x86/shadow: fix race condition sampling the dirty vram state + +d->arch.hvm_domain.dirty_vram must be read with the domain's paging lock held. + +If not, two concurrent hypercalls could both end up attempting to free +dirty_vram (the second of which will free a wild pointer), or both end up +allocating a new dirty_vram structure (the first of which will be leaked). + +This is XSA-104. + +Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> +Reviewed-by: Tim Deegan <tim@xen.org> + +--- a/xen/arch/x86/mm/shadow/common.c ++++ b/xen/arch/x86/mm/shadow/common.c +@@ -3485,7 +3485,7 @@ int shadow_track_dirty_vram(struct domai + int flush_tlb = 0; + unsigned long i; + p2m_type_t t; +- struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram; ++ struct sh_dirty_vram *dirty_vram; + struct p2m_domain *p2m = p2m_get_hostp2m(d); + + if ( end_pfn < begin_pfn || end_pfn > p2m->max_mapped_pfn + 1 ) +@@ -3495,6 +3495,8 @@ int shadow_track_dirty_vram(struct domai + p2m_lock(p2m_get_hostp2m(d)); + paging_lock(d); + ++ dirty_vram = d->arch.hvm_domain.dirty_vram; ++ + if ( dirty_vram && (!nr || + ( begin_pfn != dirty_vram->begin_pfn + || end_pfn != dirty_vram->end_pfn )) ) +--- a/xen/include/asm-x86/hvm/domain.h ++++ b/xen/include/asm-x86/hvm/domain.h +@@ -112,7 +112,7 @@ struct hvm_domain { + /* Memory ranges with pinned cache attributes. */ + struct list_head pinned_cacheattr_ranges; + +- /* VRAM dirty support. */ ++ /* VRAM dirty support. Protect with the domain paging lock. */ + struct sh_dirty_vram *dirty_vram; + + /* If one of vcpus of this domain is in no_fill_mode or |