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Commit b951242a authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

blackfin/ptrace: call find_vma with the mmap_sem held 



Performing vma lookups without taking the mm->mmap_sem is asking for
trouble.  While doing the search, the vma in question can be modified or
even removed before returning to the caller.  Take the lock (shared) in
order to avoid races while iterating through the vmacache and/or rbtree.

Signed-off-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
Cc: Steven Miao <realmz6@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cccad5b9

arch/blackfin/kernel/ptrace.c

+6 −2
Original line number Diff line number Diff line
@@ -117,6 +117,7 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data) 
int

is_user_addr_valid(struct task_struct *child, unsigned long start, unsigned long len)

{

	bool valid;

	struct vm_area_struct *vma;

	struct sram_list_struct *sraml;
@@ -124,8 +125,11 @@ is_user_addr_valid(struct task_struct *child, unsigned long start, unsigned long 
	if (start + len < start)

		return -EIO;



	down_read(&child->mm->mmap_sem);

	vma = find_vma(child->mm, start);

	if (vma && start >= vma->vm_start && start + len <= vma->vm_end)

	valid = vma && start >= vma->vm_start && start + len <= vma->vm_end;

	up_read(&child->mm->mmap_sem);

	if (valid)

		return 0;



	for (sraml = child->mm->context.sram_list; sraml; sraml = sraml->next)