6.6-stable review patch. If anyone has any objections, please let me know.
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From: Takamitsu Iwai takamitz@amazon.co.jp
[ Upstream commit da9c9c877597170b929a6121a68dcd3dd9a80f45 ]
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: 1da177e4c3f4 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/rose/rose_route.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index 42460da0854d5..6acbb795c506d 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -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); @@ -553,8 +560,12 @@ 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) { @@ -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); }