[src/trunk]: src/sys/kern thmap(9): Handle memory allocation failure in root_...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/542b5503280f
branches:  trunk
changeset: 364616:542b5503280f
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Apr 01 00:16:40 2022 +0000

description:
thmap(9): Handle memory allocation failure in root_try_put.

Reported-by: syzbot+8ded6e17a394e39d6291%syzkaller.appspotmail.com@localhost

diffstat:

 sys/kern/subr_thmap.c |  24 +++++++++++++++++-------
 1 files changed, 17 insertions(+), 7 deletions(-)

diffs (81 lines):

diff -r c7941de4b610 -r 542b5503280f sys/kern/subr_thmap.c
--- a/sys/kern/subr_thmap.c     Thu Mar 31 19:30:15 2022 +0000
+++ b/sys/kern/subr_thmap.c     Fri Apr 01 00:16:40 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_thmap.c,v 1.10 2022/02/13 19:20:33 riastradh Exp $        */
+/*     $NetBSD: subr_thmap.c,v 1.11 2022/04/01 00:16:40 riastradh Exp $        */
 
 /*-
  * Copyright (c) 2018 Mindaugas Rasiukevicius <rmind at noxt eu>
@@ -112,7 +112,7 @@
 #include "utils.h"
 #endif
 
-THMAP_RCSID("$NetBSD: subr_thmap.c,v 1.10 2022/02/13 19:20:33 riastradh Exp $");
+THMAP_RCSID("$NetBSD: subr_thmap.c,v 1.11 2022/04/01 00:16:40 riastradh Exp $");
 
 #include <crypto/blake2/blake2s.h>
 
@@ -515,7 +515,7 @@
  * => Implies release operation on success.
  * => Implies no ordering on failure.
  */
-static inline bool
+static inline int
 root_try_put(thmap_t *thmap, const thmap_query_t *query, thmap_leaf_t *leaf)
 {
        thmap_ptr_t expected;
@@ -530,7 +530,7 @@
         * this changes from null.
         */
        if (atomic_load_relaxed(&thmap->root[i])) {
-               return false;
+               return EEXIST;
        }
 
        /*
@@ -539,13 +539,16 @@
         * release it to readers.
         */
        node = node_create(thmap, NULL);
+       if (__predict_false(node == NULL)) {
+               return ENOMEM;
+       }
        slot = hashval_getl0slot(thmap, query, leaf);
        node_insert(node, slot, THMAP_GETOFF(thmap, leaf) | THMAP_LEAF_BIT);
        nptr = THMAP_GETOFF(thmap, node);
 again:
        if (atomic_load_relaxed(&thmap->root[i])) {
                thmap->ops->free(nptr, THMAP_INODE_LEN);
-               return false;
+               return EEXIST;
        }
        /* Release to subsequent consume in find_edge_node(). */
        expected = THMAP_NULL;
@@ -553,7 +556,7 @@
            nptr, memory_order_release, memory_order_relaxed)) {
                goto again;
        }
-       return true;
+       return 0;
 }
 
 /*
@@ -703,9 +706,16 @@
        /*
         * Try to insert into the root first, if its slot is empty.
         */
-       if (root_try_put(thmap, &query, leaf)) {
+       switch (root_try_put(thmap, &query, leaf)) {
+       case 0:
                /* Success: the leaf was inserted; no locking involved. */
                return val;
+       case EEXIST:
+               break;
+       case ENOMEM:
+               return NULL;
+       default:
+               __unreachable();
        }
 
        /*