diff options
Diffstat (limited to 'import-layers/meta-virtualization/recipes-extended/xen/files/0002-p2m-Check-return-value-of-p2m_set_entry-when-decreas.patch')
| -rw-r--r-- | import-layers/meta-virtualization/recipes-extended/xen/files/0002-p2m-Check-return-value-of-p2m_set_entry-when-decreas.patch | 109 |
1 files changed, 0 insertions, 109 deletions
diff --git a/import-layers/meta-virtualization/recipes-extended/xen/files/0002-p2m-Check-return-value-of-p2m_set_entry-when-decreas.patch b/import-layers/meta-virtualization/recipes-extended/xen/files/0002-p2m-Check-return-value-of-p2m_set_entry-when-decreas.patch deleted file mode 100644 index 8c850bd7f..000000000 --- a/import-layers/meta-virtualization/recipes-extended/xen/files/0002-p2m-Check-return-value-of-p2m_set_entry-when-decreas.patch +++ /dev/null @@ -1,109 +0,0 @@ -From d4bc7833707351a5341a6bdf04c752a028d9560d Mon Sep 17 00:00:00 2001 -From: George Dunlap <george.dunlap@citrix.com> -Date: Fri, 10 Nov 2017 16:53:55 +0000 -Subject: [PATCH 2/2] p2m: Check return value of p2m_set_entry() when - decreasing reservation - -If the entire range specified to p2m_pod_decrease_reservation() is marked -populate-on-demand, then it will make a single p2m_set_entry() call, -reducing its PoD entry count. - -Unfortunately, in the right circumstances, this p2m_set_entry() call -may fail. It that case, repeated calls to decrease_reservation() may -cause p2m->pod.entry_count to fall below zero, potentially tripping -over BUG_ON()s to the contrary. - -Instead, check to see if the entry succeeded, and return false if not. -The caller will then call guest_remove_page() on the gfns, which will -return -EINVAL upon finding no valid memory there to return. - -Unfortunately if the order > 0, the entry may have partially changed. -A domain_crash() is probably the safest thing in that case. - -Other p2m_set_entry() calls in the same function should be fine, -because they are writing the entry at its current order. Nonetheless, -check the return value and crash if our assumption turns otu to be -wrong. - -This is part of XSA-247. - -Reported-by: George Dunlap <george.dunlap.com> -Signed-off-by: George Dunlap <george.dunlap@citrix.com> -Reviewed-by: Jan Beulich <jbeulich@suse.com> ---- -v2: Crash the domain if we're not sure it's safe (or if we think it -can't happen) ---- - xen/arch/x86/mm/p2m-pod.c | 42 +++++++++++++++++++++++++++++++++--------- - 1 file changed, 33 insertions(+), 9 deletions(-) - -diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c -index f2ed751892..473d6a6dbf 100644 ---- a/xen/arch/x86/mm/p2m-pod.c -+++ b/xen/arch/x86/mm/p2m-pod.c -@@ -555,11 +555,23 @@ p2m_pod_decrease_reservation(struct domain *d, - - if ( !nonpod ) - { -- /* All PoD: Mark the whole region invalid and tell caller -- * we're done. */ -- p2m_set_entry(p2m, gpfn, INVALID_MFN, order, p2m_invalid, -- p2m->default_access); -- p2m->pod.entry_count-=(1<<order); -+ /* -+ * All PoD: Mark the whole region invalid and tell caller -+ * we're done. -+ */ -+ if ( p2m_set_entry(p2m, gpfn, INVALID_MFN, order, p2m_invalid, -+ p2m->default_access) ) -+ { -+ /* -+ * If this fails, we can't tell how much of the range was changed. -+ * Best to crash the domain unless we're sure a partial change is -+ * impossible. -+ */ -+ if ( order != 0 ) -+ domain_crash(d); -+ goto out_unlock; -+ } -+ p2m->pod.entry_count -= 1UL << order; - BUG_ON(p2m->pod.entry_count < 0); - ret = 1; - goto out_entry_check; -@@ -600,8 +612,14 @@ p2m_pod_decrease_reservation(struct domain *d, - n = 1UL << cur_order; - if ( t == p2m_populate_on_demand ) - { -- p2m_set_entry(p2m, gpfn + i, INVALID_MFN, cur_order, -- p2m_invalid, p2m->default_access); -+ /* This shouldn't be able to fail */ -+ if ( p2m_set_entry(p2m, gpfn + i, INVALID_MFN, cur_order, -+ p2m_invalid, p2m->default_access) ) -+ { -+ ASSERT_UNREACHABLE(); -+ domain_crash(d); -+ goto out_unlock; -+ } - p2m->pod.entry_count -= n; - BUG_ON(p2m->pod.entry_count < 0); - pod -= n; -@@ -622,8 +640,14 @@ p2m_pod_decrease_reservation(struct domain *d, - - page = mfn_to_page(mfn); - -- p2m_set_entry(p2m, gpfn + i, INVALID_MFN, cur_order, -- p2m_invalid, p2m->default_access); -+ /* This shouldn't be able to fail */ -+ if ( p2m_set_entry(p2m, gpfn + i, INVALID_MFN, cur_order, -+ p2m_invalid, p2m->default_access) ) -+ { -+ ASSERT_UNREACHABLE(); -+ domain_crash(d); -+ goto out_unlock; -+ } - p2m_tlb_flush_sync(p2m); - for ( j = 0; j < n; ++j ) - set_gpfn_from_mfn(mfn_x(mfn), INVALID_M2P_ENTRY); --- -2.15.0 - |
