linux-kernel - [PATCH] x86/kasan: panic if there is not enough memory to boot.

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Message-Id: <20180110153602.18919-1-aryabinin@virtuozzo.com>
Date:   Wed, 10 Jan 2018 18:36:02 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        kernel test robot <xiaolong.ye@...el.com>, lkp@...org,
        Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: [PATCH] x86/kasan: panic if there is not enough memory to boot.

Currently KASAN doesn't panic in case it don't have enough memory
to boot. Instead, it crashes in some random place:

 kernel BUG at arch/x86/mm/physaddr.c:27!

 RIP: 0010:__phys_addr+0x268/0x276
 Call Trace:
  kasan_populate_shadow+0x3f2/0x497
  kasan_init+0x12e/0x2b2
  setup_arch+0x2825/0x2a2c
  start_kernel+0xc8/0x15f4
  x86_64_start_reservations+0x2a/0x2c
  x86_64_start_kernel+0x72/0x75
  secondary_startup_64+0xa5/0xb0

Use memblock_virt_alloc_try_nid() for allocations without failure
fallback. It will panic with an out of memory message.

Reported-by: kernel test robot <xiaolong.ye@...el.com>
Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
---
 arch/x86/mm/kasan_init_64.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 47388f0c0e59..af6f2f9c6a26 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -21,10 +21,14 @@ extern struct range pfn_mapped[E820_MAX_ENTRIES];
 
 static p4d_t tmp_p4d_table[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
 
-static __init void *early_alloc(size_t size, int nid)
+static __init void *early_alloc(size_t size, int nid, bool panic)
 {
-	return memblock_virt_alloc_try_nid_nopanic(size, size,
-		__pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
+	if (panic)
+		return memblock_virt_alloc_try_nid(size, size,
+			__pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
+	else
+		return memblock_virt_alloc_try_nid_nopanic(size, size,
+			__pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
 }
 
 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
@@ -38,14 +42,14 @@ static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
 		if (boot_cpu_has(X86_FEATURE_PSE) &&
 		    ((end - addr) == PMD_SIZE) &&
 		    IS_ALIGNED(addr, PMD_SIZE)) {
-			p = early_alloc(PMD_SIZE, nid);
+			p = early_alloc(PMD_SIZE, nid, false);
 			if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
 				return;
 			else if (p)
 				memblock_free(__pa(p), PMD_SIZE);
 		}
 
-		p = early_alloc(PAGE_SIZE, nid);
+		p = early_alloc(PAGE_SIZE, nid, true);
 		pmd_populate_kernel(&init_mm, pmd, p);
 	}
 
@@ -57,7 +61,7 @@ static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
 		if (!pte_none(*pte))
 			continue;
 
-		p = early_alloc(PAGE_SIZE, nid);
+		p = early_alloc(PAGE_SIZE, nid, true);
 		entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
 		set_pte_at(&init_mm, addr, pte, entry);
 	} while (pte++, addr += PAGE_SIZE, addr != end);
@@ -75,14 +79,14 @@ static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
 		if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
 		    ((end - addr) == PUD_SIZE) &&
 		    IS_ALIGNED(addr, PUD_SIZE)) {
-			p = early_alloc(PUD_SIZE, nid);
+			p = early_alloc(PUD_SIZE, nid, false);
 			if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
 				return;
 			else if (p)
 				memblock_free(__pa(p), PUD_SIZE);
 		}
 
-		p = early_alloc(PAGE_SIZE, nid);
+		p = early_alloc(PAGE_SIZE, nid, true);
 		pud_populate(&init_mm, pud, p);
 	}
 
@@ -101,7 +105,7 @@ static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 	unsigned long next;
 
 	if (p4d_none(*p4d)) {
-		void *p = early_alloc(PAGE_SIZE, nid);
+		void *p = early_alloc(PAGE_SIZE, nid, true);
 
 		p4d_populate(&init_mm, p4d, p);
 	}
@@ -122,7 +126,7 @@ static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 	unsigned long next;
 
 	if (pgd_none(*pgd)) {
-		p = early_alloc(PAGE_SIZE, nid);
+		p = early_alloc(PAGE_SIZE, nid, true);
 		pgd_populate(&init_mm, pgd, p);
 	}
 
-- 
2.13.6