diff options
Diffstat (limited to 'system/xen/xsa/xsa250.patch')
| -rw-r--r-- | system/xen/xsa/xsa250.patch | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa250.patch b/system/xen/xsa/xsa250.patch new file mode 100644 index 0000000000..26aeb33fed --- /dev/null +++ b/system/xen/xsa/xsa250.patch @@ -0,0 +1,67 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: x86/shadow: fix ref-counting error handling + +The old-Linux handling in shadow_set_l4e() mistakenly ORed together the +results of sh_get_ref() and sh_pin(). As the latter failing is not a +correctness problem, simply ignore its return value. + +In sh_set_toplevel_shadow() a failing sh_get_ref() must not be +accompanied by installing the entry, despite the domain being crashed. + +This is XSA-250. + +Signed-off-by: Jan Beulich <jbeulich@suse.com> +Reviewed-by: Tim Deegan <tim@xen.org> + +--- a/xen/arch/x86/mm/shadow/multi.c ++++ b/xen/arch/x86/mm/shadow/multi.c +@@ -923,7 +923,7 @@ static int shadow_set_l4e(struct domain + shadow_l4e_t new_sl4e, + mfn_t sl4mfn) + { +- int flags = 0, ok; ++ int flags = 0; + shadow_l4e_t old_sl4e; + paddr_t paddr; + ASSERT(sl4e != NULL); +@@ -938,15 +938,16 @@ static int shadow_set_l4e(struct domain + { + /* About to install a new reference */ + mfn_t sl3mfn = shadow_l4e_get_mfn(new_sl4e); +- ok = sh_get_ref(d, sl3mfn, paddr); +- /* Are we pinning l3 shadows to handle wierd linux behaviour? */ +- if ( sh_type_is_pinnable(d, SH_type_l3_64_shadow) ) +- ok |= sh_pin(d, sl3mfn); +- if ( !ok ) ++ ++ if ( !sh_get_ref(d, sl3mfn, paddr) ) + { + domain_crash(d); + return SHADOW_SET_ERROR; + } ++ ++ /* Are we pinning l3 shadows to handle weird Linux behaviour? */ ++ if ( sh_type_is_pinnable(d, SH_type_l3_64_shadow) ) ++ sh_pin(d, sl3mfn); + } + + /* Write the new entry */ +@@ -3965,14 +3966,15 @@ sh_set_toplevel_shadow(struct vcpu *v, + + /* Take a ref to this page: it will be released in sh_detach_old_tables() + * or the next call to set_toplevel_shadow() */ +- if ( !sh_get_ref(d, smfn, 0) ) ++ if ( sh_get_ref(d, smfn, 0) ) ++ new_entry = pagetable_from_mfn(smfn); ++ else + { + SHADOW_ERROR("can't install %#lx as toplevel shadow\n", mfn_x(smfn)); + domain_crash(d); ++ new_entry = pagetable_null(); + } + +- new_entry = pagetable_from_mfn(smfn); +- + install_new_entry: + /* Done. Install it */ + SHADOW_PRINTK("%u/%u [%u] gmfn %#"PRI_mfn" smfn %#"PRI_mfn"\n", |