6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Carlos Llamas <cmllamas@xxxxxxxxxx>
commit dc8aea47b928cc153b591b3558829ce42f685074 upstream.
In binder_add_freeze_work() we iterate over the proc->nodes with the
proc->inner_lock held. However, this lock is temporarily dropped in
order to acquire the node->lock first (lock nesting order). This can
race with binder_node_release() and trigger a use-after-free:
==================================================================
BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xe4/0x19c
Write of size 4 at addr ffff53c04c29dd04 by task freeze/640
CPU: 5 UID: 0 PID: 640 Comm: freeze Not tainted 6.11.0-07343-ga727812a8d45 #17
Hardware name: linux,dummy-virt (DT)
Call trace:
_raw_spin_lock+0xe4/0x19c
binder_add_freeze_work+0x148/0x478
binder_ioctl+0x1e70/0x25ac
__arm64_sys_ioctl+0x124/0x190
Allocated by task 637:
__kmalloc_cache_noprof+0x12c/0x27c
binder_new_node+0x50/0x700
binder_transaction+0x35ac/0x6f74
binder_thread_write+0xfb8/0x42a0
binder_ioctl+0x18f0/0x25ac
__arm64_sys_ioctl+0x124/0x190
Freed by task 637:
kfree+0xf0/0x330
binder_thread_read+0x1e88/0x3a68
binder_ioctl+0x16d8/0x25ac
__arm64_sys_ioctl+0x124/0x190
==================================================================
Fix the race by taking a temporary reference on the node before
releasing the proc->inner lock. This ensures the node remains alive
while in use.
Fixes: d579b04a52a1 ("binder: frozen notification")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Acked-by: Todd Kjos <tkjos@xxxxxxxxxx>
Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240926233632.821189-2-cmllamas@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/android/binder.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 978740537a1a..4d90203ea048 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -5552,6 +5552,7 @@ static bool binder_txns_pending_ilocked(struct binder_proc *proc)
static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen)
{
+ struct binder_node *prev = NULL;
struct rb_node *n;
struct binder_ref *ref;
@@ -5560,7 +5561,10 @@ static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen)
struct binder_node *node;
node = rb_entry(n, struct binder_node, rb_node);
+ binder_inc_node_tmpref_ilocked(node);
binder_inner_proc_unlock(proc);
+ if (prev)
+ binder_put_node(prev);
binder_node_lock(node);
hlist_for_each_entry(ref, &node->refs, node_entry) {
/*
@@ -5586,10 +5590,13 @@ static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen)
}
binder_inner_proc_unlock(ref->proc);
}
+ prev = node;
binder_node_unlock(node);
binder_inner_proc_lock(proc);
}
binder_inner_proc_unlock(proc);
+ if (prev)
+ binder_put_node(prev);
}
static int binder_ioctl_freeze(struct binder_freeze_info *info,
--
2.47.1
