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authorDavidlohr Bueso <davidlohr@hp.com>2014-06-06 14:38:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-06 16:08:16 -0700
commitb951242a4f633462b9766171bc5be8a8dc3f3e12 (patch)
tree3e8dc9383920eb2c92c1820bfcebe1823cd8899e
parentcccad5b983d2b0aa453879591ac4ab1c54ff9db6 (diff)
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: Davidlohr Bueso <davidlohr@hp.com> Cc: Steven Miao <realmz6@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/blackfin/kernel/ptrace.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/blackfin/kernel/ptrace.c b/arch/blackfin/kernel/ptrace.c
index e1f88e028cfe..8b8fe671b1a6 100644
--- a/arch/blackfin/kernel/ptrace.c
+++ b/arch/blackfin/kernel/ptrace.c
@@ -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;
@@ -124,9 +125,12 @@ 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)
- return 0;
+ 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)
if (start >= (unsigned long)sraml->addr