From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBEEE5B5A9 for ; Mon, 22 Jan 2024 16:56:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705942568; cv=none; b=vAWc5MwcBTWeejFJ4hntmDDrsCm6i+lUEb5PLuyBWA2pJGZxHJ++cfikYzazC9BiHQHo81Eoshe3/568i6+t98ZgaBTLXsKX1PTfHk7SCei+T5ZSR0e2UhYJ6FsE3//f6jpnMWwz59jQAnbP4Xu5EHDJSCh+hViTthd9d594W0k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705942568; c=relaxed/simple; bh=FqjirAP+Ut/vLC3+sj0UxT8xzIfifdx3G+Yn9noN5q4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=b8jde5oq+5WyY+2kmvOD75NExFxi0/hBf2flRqFaS6rJIys1ljTJZMyhFTE2PvhJs4WZODg29xsNu2enkZDpF+ALofweVK9432mfapifyF4faKWXVoHyJ37Lcz97LEJOW8oIW88RW6d+97IZmswBggf8DctZNK0Y+TOkfadfzQc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=xxp5nVN2; arc=none smtp.client-ip=209.85.215.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="xxp5nVN2" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-5c66a69ec8eso3799933a12.3 for ; Mon, 22 Jan 2024 08:56:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1705942566; x=1706547366; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=+bgpvX7nPKDBQ/B4TZ6pXqTiQd5FJI9QOY3vZ8HezAk=; b=xxp5nVN28YsPLEOIdjG8mz33RDnZxGTqOESkx0YhllxEQuvgXcgVjwrIPulY8Kw7v9 x/tsoHgrixrymEhhI8yQdjEPRC1mGExgp8NOJSJ98gr+1sm/phVqWbnJDmerGWDjl4u9 rmv2D62BORu3cCYu9RVramZocFOuQHKdER6otixEliXBieJElSwgwZ96IJXseqgYRv2g yD9RqT4nrNMF+2r39Cp8r4hULfVTk8N9cfsL8uNAtAhFoGLLJEol5E/gK4pLVMnhsiOU Ez87hZsCm505nMpMTuKaJhDvQ4tx92cRDckBLmMvWfbo4yvFrA+Jz4RrTAR8Gc5eb5MS qjQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705942566; x=1706547366; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+bgpvX7nPKDBQ/B4TZ6pXqTiQd5FJI9QOY3vZ8HezAk=; b=axSaQbdRx7C+sV/dnbGRRakmbQF1DgQ03dpRMhUePoQHJ7+2EsLIzW0FXeBw3VIIU/ OTxBUwWlcyHBPozdaF9Mh4MwGA5oR5pxuNrAgLVQF2Q8DWcaJZHeVrTSVtOxdtGcth3n Qe1oa7dKdqKg0qNyDB+awniXHIS2u94XJGpaKGkPPUHci6l9QexukhKWAtNvnwb7+DG8 dYkWcvM5Fi8ihhYZaEyRRtx4mekbtIQ0/qnQ6Z4vY5n+iVcrRIYrKsf07Enuv30nAC8p MYqNh5kGiMyigEtEAPaOy+n7tRVvdlyIi72L7bsO7gl6m7dlyoGJ3wN8ntP/MopIuAJC Q0jQ== X-Gm-Message-State: AOJu0Yz4812/rewkAo/JVTMw0ttWg6EsmZwL/umpwQ8PuuhCn/55Jip0 rzI559fkY2RmV/dDQvoolC+lQpMwgWPAD65/raXTUpdbMctE+/n702EPHmuFqJAibsCWncw9umS +WAPpwUZUva95QkxZJlFUHtg29scQz6Zf8EyshMVJMIYRn2P0kta7yfGjjhDtbZX8WneAz0Il4v k+iLiUrW9i1ACAmKBU5L73MAFiR5YAVtF+vWZMCd2ygzo= X-Google-Smtp-Source: AGHT+IFncsRn2tdN7gPG9c0+tB8Ja+tptk4227hv4ECkQHk6a9VQ7+m67yTuaAMa/iIxT7rKx6Pc3TTJGpgdTg== X-Received: from xllamas.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5070]) (user=cmllamas job=sendgmr) by 2002:a63:4301:0:b0:5ce:6c6:6973 with SMTP id q1-20020a634301000000b005ce06c66973mr24396pga.8.1705942565609; Mon, 22 Jan 2024 08:56:05 -0800 (PST) Date: Mon, 22 Jan 2024 16:56:02 +0000 In-Reply-To: <20240118215119.1040432-1-cmllamas@google.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240118215119.1040432-1-cmllamas@google.com> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240122165603.2107402-1-cmllamas@google.com> Subject: [PATCH 5.10.y v2] binder: fix use-after-free in shinker's callback From: Carlos Llamas To: stable@vger.kernel.org Cc: Carlos Llamas , Liam Howlett , Minchan Kim , Alice Ryhl , Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" commit 3f489c2067c5824528212b0fc18b28d51332d906 upstream. The mmap read lock is used during the shrinker's callback, which means that using alloc->vma pointer isn't safe as it can race with munmap(). As of commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") the mmap lock is downgraded after the vma has been isolated. I was able to reproduce this issue by manually adding some delays and triggering page reclaiming through the shrinker's debug sysfs. The following KASAN report confirms the UAF: ================================================================== BUG: KASAN: slab-use-after-free in zap_page_range_single+0x470/0x4b8 Read of size 8 at addr ffff356ed50e50f0 by task bash/478 CPU: 1 PID: 478 Comm: bash Not tainted 6.6.0-rc5-00055-g1c8b86a3799f-dirty #70 Hardware name: linux,dummy-virt (DT) Call trace: zap_page_range_single+0x470/0x4b8 binder_alloc_free_page+0x608/0xadc __list_lru_walk_one+0x130/0x3b0 list_lru_walk_node+0xc4/0x22c binder_shrink_scan+0x108/0x1dc shrinker_debugfs_scan_write+0x2b4/0x500 full_proxy_write+0xd4/0x140 vfs_write+0x1ac/0x758 ksys_write+0xf0/0x1dc __arm64_sys_write+0x6c/0x9c Allocated by task 492: kmem_cache_alloc+0x130/0x368 vm_area_alloc+0x2c/0x190 mmap_region+0x258/0x18bc do_mmap+0x694/0xa60 vm_mmap_pgoff+0x170/0x29c ksys_mmap_pgoff+0x290/0x3a0 __arm64_sys_mmap+0xcc/0x144 Freed by task 491: kmem_cache_free+0x17c/0x3c8 vm_area_free_rcu_cb+0x74/0x98 rcu_core+0xa38/0x26d4 rcu_core_si+0x10/0x1c __do_softirq+0x2fc/0xd24 Last potentially related work creation: __call_rcu_common.constprop.0+0x6c/0xba0 call_rcu+0x10/0x1c vm_area_free+0x18/0x24 remove_vma+0xe4/0x118 do_vmi_align_munmap.isra.0+0x718/0xb5c do_vmi_munmap+0xdc/0x1fc __vm_munmap+0x10c/0x278 __arm64_sys_munmap+0x58/0x7c Fix this issue by performing instead a vma_lookup() which will fail to find the vma that was isolated before the mmap lock downgrade. Note that this option has better performance than upgrading to a mmap write lock which would increase contention. Plus, mmap_write_trylock() has been recently removed anyway. Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") Cc: stable@vger.kernel.org Cc: Liam Howlett Cc: Minchan Kim Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20231201172212.1813387-3-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman [cmllamas: use find_vma() instead of vma_lookup() as commit ce6d42f2e4a2 is missing in v5.10. This only works because we check the vma against our cached alloc->vma pointer.] Signed-off-by: Carlos Llamas --- Notes: v2: remove leftover cherry-pick line from commit log drivers/android/binder_alloc.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index b6bf9caaf1d1..61406bfa454b 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -1002,7 +1002,9 @@ enum lru_status binder_alloc_free_page(struct list_head *item, goto err_mmget; if (!mmap_read_trylock(mm)) goto err_mmap_read_lock_failed; - vma = binder_alloc_get_vma(alloc); + vma = find_vma(mm, page_addr); + if (vma && vma != binder_alloc_get_vma(alloc)) + goto err_invalid_vma; list_lru_isolate(lru, item); spin_unlock(lock); @@ -1028,6 +1030,8 @@ enum lru_status binder_alloc_free_page(struct list_head *item, mutex_unlock(&alloc->mutex); return LRU_REMOVED_RETRY; +err_invalid_vma: + mmap_read_unlock(mm); err_mmap_read_lock_failed: mmput_async(mm); err_mmget: -- 2.43.0.429.g432eaa2c6b-goog