diff options
Diffstat (limited to 'system/xen/xsa/xsa249.patch')
| -rw-r--r-- | system/xen/xsa/xsa249.patch | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa249.patch b/system/xen/xsa/xsa249.patch new file mode 100644 index 0000000000000..ecfa4305e5bfb --- /dev/null +++ b/system/xen/xsa/xsa249.patch @@ -0,0 +1,42 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: x86/shadow: fix refcount overflow check + +Commit c385d27079 ("x86 shadow: for multi-page shadows, explicitly track +the first page") reduced the refcount width to 25, without adjusting the +overflow check. Eliminate the disconnect by using a manifest constant. + +Interestingly, up to commit 047782fa01 ("Out-of-sync L1 shadows: OOS +snapshot") the refcount was 27 bits wide, yet the check was already +using 26. + +This is XSA-249. + +Signed-off-by: Jan Beulich <jbeulich@suse.com> +Reviewed-by: George Dunlap <george.dunlap@citrix.com> +Reviewed-by: Tim Deegan <tim@xen.org> +--- +v2: Simplify expression back to the style it was. + +--- a/xen/arch/x86/mm/shadow/private.h ++++ b/xen/arch/x86/mm/shadow/private.h +@@ -529,7 +529,7 @@ static inline int sh_get_ref(struct doma + x = sp->u.sh.count; + nx = x + 1; + +- if ( unlikely(nx >= 1U<<26) ) ++ if ( unlikely(nx >= (1U << PAGE_SH_REFCOUNT_WIDTH)) ) + { + SHADOW_PRINTK("shadow ref overflow, gmfn=%lx smfn=%lx\n", + __backpointer(sp), mfn_x(smfn)); +--- a/xen/include/asm-x86/mm.h ++++ b/xen/include/asm-x86/mm.h +@@ -82,7 +82,8 @@ struct page_info + unsigned long type:5; /* What kind of shadow is this? */ + unsigned long pinned:1; /* Is the shadow pinned? */ + unsigned long head:1; /* Is this the first page of the shadow? */ +- unsigned long count:25; /* Reference count */ ++#define PAGE_SH_REFCOUNT_WIDTH 25 ++ unsigned long count:PAGE_SH_REFCOUNT_WIDTH; /* Reference count */ + } sh; + + /* Page is on a free list: ((count_info & PGC_count_mask) == 0). */ |