linux-kernel - [PATCH 4.9 12/39] kaiser: ENOMEM if kaiser_pagetable

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Date:   Wed,  3 Jan 2018 21:11:26 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hugh Dickins <hughd@...gle.com>
Subject: [PATCH 4.9 12/39] kaiser: ENOMEM if kaiser_pagetable_walk() NULL

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hugh Dickins <hughd@...gle.com>


kaiser_add_user_map() took no notice when kaiser_pagetable_walk() failed.
And avoid its might_sleep() when atomic (though atomic at present unused).

Signed-off-by: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/mm/kaiser.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -98,11 +98,11 @@ static pte_t *kaiser_pagetable_walk(unsi
 	pgd_t *pgd = native_get_shadow_pgd(pgd_offset_k(address));
 	gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO);
 
-	might_sleep();
 	if (is_atomic) {
 		gfp &= ~GFP_KERNEL;
 		gfp |= __GFP_HIGH | __GFP_ATOMIC;
-	}
+	} else
+		might_sleep();
 
 	if (pgd_none(*pgd)) {
 		WARN_ONCE(1, "All shadow pgds should have been populated");
@@ -159,13 +159,17 @@ int kaiser_add_user_map(const void *__st
 	unsigned long end_addr = PAGE_ALIGN(start_addr + size);
 	unsigned long target_address;
 
-	for (;address < end_addr; address += PAGE_SIZE) {
+	for (; address < end_addr; address += PAGE_SIZE) {
 		target_address = get_pa_from_mapping(address);
 		if (target_address == -1) {
 			ret = -EIO;
 			break;
 		}
 		pte = kaiser_pagetable_walk(address, false);
+		if (!pte) {
+			ret = -ENOMEM;
+			break;
+		}
 		if (pte_none(*pte)) {
 			set_pte(pte, __pte(flags | target_address));
 		} else {