restrict reading from /proc/<pid>/maps to those who share ->mm or can ptrace pid
Contents of /proc/*/maps is sensitive and may become sensitive after
open() (e.g. if target originally shares our ->mm and later does exec
on suid-root binary).
Check at read() (actually, ->start() of iterator) time that mm_struct
we'd grabbed and locked is
- still the ->mm of target
- equal to reader's ->mm or the target is ptracable by reader.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index d8b8c71..1932c2c 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -165,15 +165,13 @@
if (!priv->task)
return NULL;
- mm = get_task_mm(priv->task);
+ mm = mm_for_maps(priv->task);
if (!mm) {
put_task_struct(priv->task);
priv->task = NULL;
return NULL;
}
- down_read(&mm->mmap_sem);
-
/* start from the Nth VMA */
for (vml = mm->context.vmlist; vml; vml = vml->next)
if (n-- == 0)