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Commit e38da592 authored by Török Edwin's avatar Török Edwin Committed by Ingo Molnar
Browse files

tracing/stack-tracer: avoid races accessing file 



Impact: fix race

vma->vm_file reference is only stable while holding the mmap_sem,
so move usage of it to within the critical section.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 8d26487f

kernel/trace/trace.c

+5 −5
Original line number Original line Diff line number Diff line
@@ -1470,13 +1470,13 @@ static inline int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm, 
			file = vma->vm_file;

			file = vma->vm_file;

			vmstart = vma->vm_start;

			vmstart = vma->vm_start;

		}

		}

		up_read(&mm->mmap_sem);

	}

		if (file) {

		if (file) {

			ret = trace_seq_path(s, &file->f_path);

			ret = trace_seq_path(s, &file->f_path);

			if (ret)

			if (ret)

				ret = trace_seq_printf(s, "[+0x%lx]", ip - vmstart);

				ret = trace_seq_printf(s, "[+0x%lx]", ip - vmstart);

		}

		}

		up_read(&mm->mmap_sem);

	}

	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))

	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))

		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);

		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);

	return ret;

	return ret;