From e77aff5528a183462714f750e45add6cc71e276a Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 30 Jan 2025 21:58:22 +0000 Subject: [PATCH] binderfs: fix use-after-free in binder_devices Devices created through binderfs are added to the global binder_devices list but are not removed before being destroyed. This leads to dangling pointers in the list and subsequent use-after-free errors: ================================================================== BUG: KASAN: slab-use-after-free in binder_add_device+0x5c/0x9c Write of size 8 at addr ffff0000c258d708 by task mount/653 CPU: 7 UID: 0 PID: 653 Comm: mount Not tainted 6.13.0-09030-g6d61a53dd6f5 #1 Hardware name: linux,dummy-virt (DT) Call trace: binder_add_device+0x5c/0x9c binderfs_binder_device_create+0x690/0x84c [...] __arm64_sys_mount+0x324/0x3bc Allocated by task 632: binderfs_binder_device_create+0x168/0x84c binder_ctl_ioctl+0xfc/0x184 [...] __arm64_sys_ioctl+0x110/0x150 Freed by task 649: kfree+0xe0/0x338 binderfs_evict_inode+0x138/0x1dc [...] ================================================================== Remove devices from binder_devices before destroying them. Cc: Li Li Reported-by: syzbot+7015dcf45953112c8b45@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7015dcf45953112c8b45 Fixes: 12d909cac1e1 ("binderfs: add new binder devices to binder_devices") Signed-off-by: Carlos Llamas Tested-by: syzbot+7015dcf45953112c8b45@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20250130215823.1518990-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binderfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c index bc6bae76ccaf..94c6446604fc 100644 --- a/drivers/android/binderfs.c +++ b/drivers/android/binderfs.c @@ -274,6 +274,7 @@ static void binderfs_evict_inode(struct inode *inode) mutex_unlock(&binderfs_minors_mutex); if (refcount_dec_and_test(&device->ref)) { + hlist_del_init(&device->hlist); kfree(device->context.name); kfree(device); } -- 2.20.1