63 lines
2.3 KiB
Diff
63 lines
2.3 KiB
Diff
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# Commit 343cad8c70585c4dba8afc75e1ec1b7610605ab2
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# Date 2013-10-28 12:00:36 +0100
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# Author Jan Beulich <jbeulich@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86: refine address validity checks before accessing page tables
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In commit 40d66baa ("x86: correct LDT checks") and d06a0d71 ("x86: add
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address validity check to guest_map_l1e()") I didn't really pay
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attention to the fact that these checks would better be done before the
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paging_mode_translate() ones, as there's also no equivalent check down
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the shadow code paths involved here (at least not up to the first use
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of the address), and such generic checks shouldn't really be done by
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particular backend functions anyway.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Acked-by: Tim Deegan <tim@xen.org>
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--- a/xen/include/asm-x86/paging.h
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+++ b/xen/include/asm-x86/paging.h
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@@ -356,12 +356,14 @@ guest_map_l1e(struct vcpu *v, unsigned l
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{
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l2_pgentry_t l2e;
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+ if ( unlikely(!__addr_ok(addr)) )
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+ return NULL;
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+
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if ( unlikely(paging_mode_translate(v->domain)) )
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return paging_get_hostmode(v)->guest_map_l1e(v, addr, gl1mfn);
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/* Find this l1e and its enclosing l1mfn in the linear map */
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- if ( !__addr_ok(addr) ||
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- __copy_from_user(&l2e,
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+ if ( __copy_from_user(&l2e,
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&__linear_l2_table[l2_linear_offset(addr)],
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sizeof(l2_pgentry_t)) != 0 )
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return NULL;
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@@ -382,16 +384,21 @@ guest_unmap_l1e(struct vcpu *v, void *p)
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/* Read the guest's l1e that maps this address. */
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static inline void
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-guest_get_eff_l1e(struct vcpu *v, unsigned long addr, void *eff_l1e)
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+guest_get_eff_l1e(struct vcpu *v, unsigned long addr, l1_pgentry_t *eff_l1e)
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{
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+ if ( unlikely(!__addr_ok(addr)) )
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+ {
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+ *eff_l1e = l1e_empty();
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+ return;
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+ }
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+
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if ( likely(!paging_mode_translate(v->domain)) )
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{
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ASSERT(!paging_mode_external(v->domain));
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- if ( !__addr_ok(addr) ||
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- __copy_from_user(eff_l1e,
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+ if ( __copy_from_user(eff_l1e,
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&__linear_l1_table[l1_linear_offset(addr)],
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sizeof(l1_pgentry_t)) != 0 )
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- *(l1_pgentry_t *)eff_l1e = l1e_empty();
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+ *eff_l1e = l1e_empty();
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return;
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}
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