/proc/*/environ: wrong placing of ptrace_may_attach() check
It's a bit dopey-looking and can permit a task to cause a pagefault in an mm
which it doesn't have permission to read from.
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 46ea5d5..d092194 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -204,12 +204,17 @@
int res = 0;
struct mm_struct *mm = get_task_mm(task);
if (mm) {
- unsigned int len = mm->env_end - mm->env_start;
+ unsigned int len;
+
+ res = -ESRCH;
+ if (!ptrace_may_attach(task))
+ goto out;
+
+ len = mm->env_end - mm->env_start;
if (len > PAGE_SIZE)
len = PAGE_SIZE;
res = access_process_vm(task, mm->env_start, buffer, len, 0);
- if (!ptrace_may_attach(task))
- res = -ESRCH;
+out:
mmput(mm);
}
return res;