write in 30M

hc

2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/arch/s390/mm/mmap.c
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@@ -17,25 +17,14 @@
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 #include <linux/random.h>
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 #include <linux/compat.h>
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 #include <linux/security.h>
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-#include <asm/pgalloc.h>
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 #include <asm/elf.h>
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 static unsigned long stack_maxrandom_size(void)
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 {
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 	if (!(current->flags & PF_RANDOMIZE))
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 		return 0;
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-	if (current->personality & ADDR_NO_RANDOMIZE)
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-		return 0;
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 	return STACK_RND_MASK << PAGE_SHIFT;
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 }
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-
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-/*
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- * Top of mmap area (just below the process stack).
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- *
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- * Leave at least a ~32 MB hole.
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- */
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-#define MIN_GAP (32*1024*1024)
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-#define MAX_GAP (STACK_TOP/6*5)
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 static inline int mmap_is_legacy(struct rlimit *rlim_stack)
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 {
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@@ -60,23 +49,35 @@
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 				      struct rlimit *rlim_stack)
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 {
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 	unsigned long gap = rlim_stack->rlim_cur;
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+	unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
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+	unsigned long gap_min, gap_max;
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-	if (gap < MIN_GAP)
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-		gap = MIN_GAP;
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-	else if (gap > MAX_GAP)
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-		gap = MAX_GAP;
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-	gap &= PAGE_MASK;
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-	return STACK_TOP - stack_maxrandom_size() - rnd - gap;
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+	/* Values close to RLIM_INFINITY can overflow. */
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+	if (gap + pad > gap)
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+		gap += pad;
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+
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+	/*
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+	 * Top of mmap area (just below the process stack).
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+	 * Leave at least a ~32 MB hole.
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+	 */
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+	gap_min = 32 * 1024 * 1024UL;
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+	gap_max = (STACK_TOP / 6) * 5;
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+
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+	if (gap < gap_min)
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+		gap = gap_min;
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+	else if (gap > gap_max)
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+		gap = gap_max;
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+
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+	return PAGE_ALIGN(STACK_TOP - gap - rnd);
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 }
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-unsigned long
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-arch_get_unmapped_area(struct file *filp, unsigned long addr,
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-		unsigned long len, unsigned long pgoff, unsigned long flags)
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+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
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+				     unsigned long len, unsigned long pgoff,
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+				     unsigned long flags)
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 {
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 	struct mm_struct *mm = current->mm;
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 	struct vm_area_struct *vma;
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 	struct vm_unmapped_area_info info;
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-	int rc;
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 	if (len > TASK_SIZE - mmap_min_addr)
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 		return -ENOMEM;
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@@ -102,30 +103,20 @@
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 		info.align_mask = 0;
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 	info.align_offset = pgoff << PAGE_SHIFT;
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 	addr = vm_unmapped_area(&info);
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-	if (addr & ~PAGE_MASK)
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+	if (offset_in_page(addr))
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 		return addr;
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 check_asce_limit:
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-	if (addr + len > current->mm->context.asce_limit &&
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-	    addr + len <= TASK_SIZE) {
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-		rc = crst_table_upgrade(mm, addr + len);
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-		if (rc)
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-			return (unsigned long) rc;
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-	}
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-
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-	return addr;
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+	return check_asce_limit(mm, addr, len);
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 }
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-unsigned long
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-arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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-			  const unsigned long len, const unsigned long pgoff,
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-			  const unsigned long flags)
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+unsigned long arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
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+					     unsigned long len, unsigned long pgoff,
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+					     unsigned long flags)
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 {
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 	struct vm_area_struct *vma;
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 	struct mm_struct *mm = current->mm;
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-	unsigned long addr = addr0;
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 	struct vm_unmapped_area_info info;
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-	int rc;
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 	/* requested length too big for entire address space */
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 	if (len > TASK_SIZE - mmap_min_addr)
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@@ -160,25 +151,18 @@
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 	 * can happen with large stack limits and large mmap()
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 	 * allocations.
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 	 */
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-	if (addr & ~PAGE_MASK) {
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+	if (offset_in_page(addr)) {
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 		VM_BUG_ON(addr != -ENOMEM);
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 		info.flags = 0;
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 		info.low_limit = TASK_UNMAPPED_BASE;
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 		info.high_limit = TASK_SIZE;
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 		addr = vm_unmapped_area(&info);
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-		if (addr & ~PAGE_MASK)
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+		if (offset_in_page(addr))
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 			return addr;
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 	}
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 check_asce_limit:
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-	if (addr + len > current->mm->context.asce_limit &&
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-	    addr + len <= TASK_SIZE) {
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-		rc = crst_table_upgrade(mm, addr + len);
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-		if (rc)
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-			return (unsigned long) rc;
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-	}
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-
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-	return addr;
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+	return check_asce_limit(mm, addr, len);
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 }
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 /*