From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 C13E632193 for ; Thu, 18 Jan 2024 21:51:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705614685; cv=none; b=KaJ9Q1moXkY8c+UY7l5Mwf7xtZ/CCWAy9YfRLViNUXvyQloVQVKJu3Cz45JQ5tdPASUVfB+SLnQuLQC6INLKzs8SVCS1CKEilVJEQuMJtNYq9CO7YQuetYS9gLSDTnIjl0WzACTriFYuZSvioxxuQRLrd94N0KIXIIaURH4l/kE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705614685; c=relaxed/simple; bh=AWjc/5pSQC/fXekBaY9x5AcXjvK6JQ2ukKnkRouiS3A=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=Pzz4vrh9OLWoNpsY7Ri+XrGb1ztSqDajRTNJM+fCw0cggbTfYy0/GVmwulC1CZ8K0sgiKfxuD0VV5Oo9pLC5cWlhfmtLx2Eh8fkasMkux9WS3P+Sy2oBqgATfP15C5+FjM7mv0aMC1Sj/PMCuqLZFsEVUfpnC+tzoe2d1zdiHVg= 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=rSRSVcjE; arc=none smtp.client-ip=209.85.219.201 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="rSRSVcjE" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-dc265e24eccso39279276.0 for ; Thu, 18 Jan 2024 13:51:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1705614682; x=1706219482; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=txIFeJvia0pMllsmsZtmcaqJmLFp22N+ZM+37AjL20g=; b=rSRSVcjEL0445bMtNe50cJ0YbWSNLZunUJizBC2DgGUHc1Ac5amPM01CZ1Z3VdwiDZ BQtS2Qn3x9KmgZqiokNw2oa5Vc5UD52Til7ncoyQIJ2JNmVy3elLSNTuIzpLoU7TIrZS YMwc9i14ayFclwsoelhI/UkKJAAB87KNy+RTs2KlJ9Cb2kwI+6BL0OQSxnS1Xr2BbBVP TScSRd7rp3GgKCUJulB1pdlVNbKvFUwwSDHfAuHQjfYdw3MULv9ERUVEAyjVrSTFUU7J RLOY0EQxCNzq2q0Nn3yVuE0cSbqMfQmdWgvYcNcHmDYKfK6jE51Q8ghHV/0ycU4pmGFP LDsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705614682; x=1706219482; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=txIFeJvia0pMllsmsZtmcaqJmLFp22N+ZM+37AjL20g=; b=JH1lDKZ1rMeLbTGsIFRRuT3DtYXOwRvekaEXxmrg3K+rPwNYx30sH3K4OacXeEPmED f1H3qp5BVVBjpn+vvAA5B01wXmF+9I2ZSsCrq73oTh3pyDDNuRFoPEwLEnw1AdlJmPsj ZXjB7RzFEY6f35+2V9qWFtDBU7KXvB+5ct4bSMWFd24UDlzUdfWizF58nGNtcMUEzk29 MzjvxHV9CII5vC5ToUM8x4r7eYu6CvXPUhG7gcOhdTvQuKEsXDA6HMdBW8dtWh6HaIOe PSkj9U+9fskSItPyq/Ix/4ITABrh5oCCxNdd5O0WiZVtrnwu/7Frxzuz5EhLKp7aCX0p pUTw== X-Gm-Message-State: AOJu0YypnuW4eHA3+3Exym7OUxnSNmyHtIR3jMquiWWdaYY/A7BveO5O twgk8pZ/icw6+3/Hr/SNazCtH78QpSjSeu+JeCEjoV/riE8I2A4SRbhM17QG3Z3Yio1gFbL7FtJ dhDIofeHAtXC/DCANPj6WXsHm1ociJlZfHgZ1U8VBK/pJek9ubzFNdvubZG8k564K4nuwW1wXRR uwawkII3eI2WIJLzQ0oaAhHuMb67ll3m/xz1XWw0ofnRc= X-Google-Smtp-Source: AGHT+IGFO6zJzhif68HqhsZHjZDnz3M7neBTxhVtiBgpNDFxePU9rRHsSVcV7y5YBbYgJl/CdlpCuwSps4b6bQ== X-Received: from xllamas.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5070]) (user=cmllamas job=sendgmr) by 2002:a25:26d0:0:b0:dc2:3441:897f with SMTP id m199-20020a2526d0000000b00dc23441897fmr646708ybm.6.1705614682750; Thu, 18 Jan 2024 13:51:22 -0800 (PST) Date: Thu, 18 Jan 2024 21:51:19 +0000 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240118215119.1040432-1-cmllamas@google.com> Subject: [PATCH 5.10.y] 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 (cherry picked from commit aaa8cde67eba56b3ebe8c2c155e896f9ccaa8bb7) --- 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