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net: rose: include node references in rose_neigh refcount

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Current implementation maintains two separate reference counting
mechanisms: the 'count' field in struct rose_neigh tracks references from
rose_node structures, while the 'use' field (now refcount_t) tracks
references from rose_sock.

This patch merges these two reference counting systems using 'use' field
for proper reference management. Specifically, this patch adds incrementing
and decrementing of rose_neigh->use when rose_neigh->count is incremented
or decremented.

This patch also modifies rose_rt_free(), rose_rt_device_down() and
rose_clear_route() to properly release references to rose_neigh objects
before freeing a rose_node through rose_remove_node().

These changes ensure rose_neigh structures are properly freed only when
all references, including those from rose_node structures, are released.
As a result, this resolves a slab-use-after-free issue reported by Syzbot.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: syzbot+942297eecf7d2d61d1f1@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=942297eecf7d2d61d1f1
Signed-off-by: Takamitsu Iwai <takamitz@amazon.co.jp>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250823085857.47674-4-takamitz@amazon.co.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Takamitsu Iwai 2025-08-23 17:58:57 +09:00 committed by Jakub Kicinski
parent d860d1faa6
commit da9c9c8775
1 changed files with 16 additions and 2 deletions
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18
net/rose/rose_route.c
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@ -178,6 +178,7 @@ static int __must_check rose_add_node(struct rose_route_struct *rose_route,
}
}
rose_neigh->count++;
rose_neigh_hold(rose_neigh);
goto out;
}
@ -187,6 +188,7 @@ static int __must_check rose_add_node(struct rose_route_struct *rose_route,
rose_node->neighbour[rose_node->count] = rose_neigh;
rose_node->count++;
rose_neigh->count++;
rose_neigh_hold(rose_neigh);
}
out:
@ -322,6 +324,7 @@ static int rose_del_node(struct rose_route_struct *rose_route,
for (i = 0; i < rose_node->count; i++) {
if (rose_node->neighbour[i] == rose_neigh) {
rose_neigh->count--;
rose_neigh_put(rose_neigh);
if (rose_neigh->count == 0) {
rose_remove_neigh(rose_neigh);
@ -430,6 +433,7 @@ int rose_add_loopback_node(const rose_address *address)
rose_node_list = rose_node;
rose_loopback_neigh->count++;
rose_neigh_hold(rose_loopback_neigh);
out:
spin_unlock_bh(&rose_node_list_lock);
@ -461,6 +465,7 @@ void rose_del_loopback_node(const rose_address *address)
rose_remove_node(rose_node);
rose_loopback_neigh->count--;
rose_neigh_put(rose_loopback_neigh);
out:
spin_unlock_bh(&rose_node_list_lock);
@ -500,6 +505,7 @@ void rose_rt_device_down(struct net_device *dev)
memmove(&t->neighbour[i], &t->neighbour[i + 1],
sizeof(t->neighbour[0]) *
(t->count - i));
rose_neigh_put(s);
}
if (t->count <= 0)
@ -543,6 +549,7 @@ static int rose_clear_routes(void)
{
struct rose_neigh *s, *rose_neigh;
struct rose_node *t, *rose_node;
int i;
spin_lock_bh(&rose_node_list_lock);
spin_lock_bh(&rose_neigh_list_lock);
@ -553,9 +560,13 @@ static int rose_clear_routes(void)
while (rose_node != NULL) {
t = rose_node;
rose_node = rose_node->next;
if (!t->loopback)
if (!t->loopback) {
for (i = 0; i < rose_node->count; i++)
rose_neigh_put(t->neighbour[i]);
rose_remove_node(t);
}
}
while (rose_neigh != NULL) {
s = rose_neigh;
@ -1189,7 +1200,7 @@ static int rose_neigh_show(struct seq_file *seq, void *v)
(rose_neigh->loopback) ? "RSLOOP-0" : ax2asc(buf, &rose_neigh->callsign),
rose_neigh->dev ? rose_neigh->dev->name : "???",
rose_neigh->count,
refcount_read(&rose_neigh->use) - 1,
refcount_read(&rose_neigh->use) - rose_neigh->count - 1,
(rose_neigh->dce_mode) ? "DCE" : "DTE",
(rose_neigh->restarted) ? "yes" : "no",
ax25_display_timer(&rose_neigh->t0timer) / HZ,
@ -1294,6 +1305,7 @@ void __exit rose_rt_free(void)
struct rose_neigh *s, *rose_neigh = rose_neigh_list;
struct rose_node *t, *rose_node = rose_node_list;
struct rose_route *u, *rose_route = rose_route_list;
int i;
while (rose_neigh != NULL) {
s = rose_neigh;
@ -1307,6 +1319,8 @@ void __exit rose_rt_free(void)
t = rose_node;
rose_node = rose_node->next;
for (i = 0; i < t->count; i++)
rose_neigh_put(t->neighbour[i]);
rose_remove_node(t);
}