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.
This patch is completely *untested*. Signed-off-by: Davidlohr Bueso <davidl...@hp.com> Cc: Steven Miao <real...@gmail.com> Cc: adi-buildroot-de...@lists.sourceforge.net --- arch/blackfin/kernel/ptrace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/blackfin/kernel/ptrace.c b/arch/blackfin/kernel/ptrace.c index e1f88e0..8b8fe67 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 -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/