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Subject[PATCH 5/5] mm/vmalloc.c: avoid endless loop under v[un]mapping improper ranges
Date
From: zijun_hu <zijun_hu@htc.com>

fix the following bug:
- endless loop maybe happen when v[un]mapping improper ranges
whose either boundary is not aligned to page

Signed-off-by: zijun_hu <zijun_hu@htc.com>
---
mm/vmalloc.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5eeecc3..16fe957 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -67,7 +67,7 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
do {
pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
WARN_ON(!pte_none(ptent) && !pte_present(ptent));
- } while (pte++, addr += PAGE_SIZE, addr != end);
+ } while (pte++, addr += PAGE_SIZE, addr < end && addr >= PAGE_SIZE);
}

static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end)
@@ -108,6 +108,9 @@ static void vunmap_page_range(unsigned long addr, unsigned long end)
unsigned long next;

BUG_ON(addr >= end);
+ WARN_ON(!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(end));
+
+ addr = round_down(addr, PAGE_SIZE);
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
@@ -139,7 +142,7 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
return -ENOMEM;
set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
(*nr)++;
- } while (pte++, addr += PAGE_SIZE, addr != end);
+ } while (pte++, addr += PAGE_SIZE, addr < end);
return 0;
}

@@ -193,6 +196,8 @@ static int vmap_page_range_noflush(unsigned long start, unsigned long end,
int nr = 0;

BUG_ON(addr >= end);
+ BUG_ON(!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(end));
+
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
--
1.9.1
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