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FROMGIT: binder: fix node UAF in binder_add_freeze_work()

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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@vger.kernel.org
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20240926233632.821189-2-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 366003708
(cherry picked from commit dc8aea47b928cc153b591b3558829ce42f685074
 git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
 char-misc-next)
Change-Id: I47b053532dd4cd3424d35d6f254ca4d00c426411
Signed-off-by: Carlos Llamas <cmllamas@google.com>
This commit is contained in:
Carlos Llamas 2024-09-26 23:36:12 +00:00
parent e733b347fb
commit 8f52d7a1ee
1 changed files with 7 additions and 0 deletions
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7
drivers/android/binder.c
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@ -5558,6 +5558,7 @@ 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;
@ -5566,7 +5567,10 @@ 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) {
/*
@ -5592,10 +5596,13 @@ 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,