blob: da62c0c83656bcfe8e8c5a6031b47d096a8794c7 [file] [log] [blame]
From c6eb2b21e572604da376fae116352522d4f0a83d Mon Sep 17 00:00:00 2001
From: Randy Dunlap <rdunlap@infradead.org>
Date: Wed, 1 Apr 2020 21:10:58 -0700
Subject: [PATCH] mm: mempolicy: require at least one nodeid for MPOL_PREFERRED
commit aa9f7d5172fac9bf1f09e678c35e287a40a7b7dd upstream.
Using an empty (malformed) nodelist that is not caught during mount option
parsing leads to a stack-out-of-bounds access.
The option string that was used was: "mpol=prefer:,". However,
MPOL_PREFERRED requires a single node number, which is not being provided
here.
Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's
nodeid.
Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display")
Reported-by: Entropy Moe <3ntr0py1337@gmail.com>
Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c8c8ec6e788a..b28d0616f002 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2812,7 +2812,9 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
switch (mode) {
case MPOL_PREFERRED:
/*
- * Insist on a nodelist of one node only
+ * Insist on a nodelist of one node only, although later
+ * we use first_node(nodes) to grab a single node, so here
+ * nodelist (or nodes) cannot be empty.
*/
if (nodelist) {
char *rest = nodelist;
@@ -2820,6 +2822,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
rest++;
if (*rest)
goto out;
+ if (nodes_empty(nodes))
+ goto out;
}
break;
case MPOL_INTERLEAVE:
--
2.7.4