| From: Randy Dunlap <rdunlap@infradead.org> |
| Date: Wed, 1 Apr 2020 21:10:58 -0700 |
| Subject: 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: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| mm/mempolicy.c | 6 +++++- |
| 1 file changed, 5 insertions(+), 1 deletion(-) |
| |
| --- a/mm/mempolicy.c |
| +++ b/mm/mempolicy.c |
| @@ -2711,7 +2711,9 @@ int mpol_parse_str(char *str, struct mem |
| 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; |
| @@ -2719,6 +2721,8 @@ int mpol_parse_str(char *str, struct mem |
| rest++; |
| if (*rest) |
| goto out; |
| + if (nodes_empty(nodes)) |
| + goto out; |
| } |
| break; |
| case MPOL_INTERLEAVE: |
