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authorRandy Dunlap <rdunlap@infradead.org>2020-04-01 21:10:58 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-04-08 09:11:09 +0200
commit3c216b36aae719029f0431c67500d4eef9f77dd6 (patch)
treed08ea4588f3be38301483b0840a8a9a30c36a37e
parent333d4e5cca7b8ef1b9e2a348806840726148a6fc (diff)
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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> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--mm/mempolicy.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 977c641f78cf..f93b52bf6ffc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2841,7 +2841,9 @@ 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;
@@ -2849,6 +2851,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
rest++;
if (*rest)
goto out;
+ if (nodes_empty(nodes))
+ goto out;
}
break;
case MPOL_INTERLEAVE: