From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (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 B88592C197 for ; Thu, 18 Jan 2024 21:43:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705614193; cv=none; b=KxXkrDt2mLD65v1QOfqtU+A/ENsRgstdqOJ8e0QPSrJoxugx2o3p9kHV64PG2sjBsZLCkgo/zjS2e0MRml6YPR+XOjCODiyv4HQH4ziXoJV4nJo/ePiCXozVyWAeYe3sCbUCMkNJ2ofFnbr0Ko/Wxwbzvt+8qcwRZyHYKNzEBgI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705614193; c=relaxed/simple; bh=j8yOfncxkjjdOCkRzCJpbak8qwTBuE+nUC17WZq1y3U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=qx5R0wTcli/EvE7ldXPoLomF3kMsLlOf8us7cBgDgsd0HDqzQ054HCmxJAQanMpNEz9/HjntTbOD65J3XSeLhcnKl1GjKLpGM1LLlxNhlrK3d47Ydu7In/iawXECUxpocIyVSMmY+UhpqxaNsJp7whlQRbwHzYdoks6SPuIjwIM= 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=ru49Vsla; arc=none smtp.client-ip=209.85.128.202 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="ru49Vsla" Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-5e617562a65so1860977b3.1 for ; Thu, 18 Jan 2024 13:43:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1705614190; x=1706218990; 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=6Co98/eaTR5iaXZeYgbld8aWqZnRUEzyOIm0WUOGIVo=; b=ru49VslaxHTZWzHBDQ82vpvFj1wCgSJKLH0kNZUJYObbNLJh8SgngjjNtII4W+meoh zlptr01+Al9GfemTXezUDQCsHEPB/DPIUZ9dSKCfTQcmPLJRlVmvc5eNpKGDxelHDhQJ /k+oGoXCUnhZfzqY/FG3eR9lrAas1+bQEewTp/HlsS/Zqp4wy7hgpFk2vzi6I7VjoG+U UNC4iqC8pUEfnBMMfZgpxI9Z4z81tkVmwBBroRRPpiWqrraCxj/1rZeHTUgNvxTIMxsa 9xFoHaI41IGAo7Z/EozUPMUuAcWjJfKXMprj23VABvS4hexxeEafbrvHfZVyQr/n7ip2 fm4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705614190; x=1706218990; 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=6Co98/eaTR5iaXZeYgbld8aWqZnRUEzyOIm0WUOGIVo=; b=eVoAoJUNoHF3N5Ltf6yk+bIrl6iuMxqCUp2Mrr/edsH1TbBOfFv4MrNhh885JANd1f TZdshCwYOrW6tcZFm7qol7lFn0WupNrh3YlUXQGv8lYnWRqJI1msRW2m7u5opKonSjzV NRGM62zi1nVC9eF40/JEDxSO+YB72A8ACh5iHnTzbri6cIPojYY6EA9LedwE+dnyzmRb FJRvKGZYwQ9pHH1RR9FI2xSj2ibkweXpozlJDzx+FxuOeR3JsaXiSg9fBLED+xsVg0Tg 8ZKfDD0To1iMqgC84YVJOe3U+a4tLMMu3uEj0Mws5K5KoHSokbEO554Jgotuuf27NgWC hdRQ== X-Gm-Message-State: AOJu0YxboLcwRYzl0t0iiBF47dEKzSLedO0jb0XwhEWVRCCazM0pkjdH sL8JXfqOLvj4w737YvXf+IzzKr3YeZd7eEh8/Eg1okTADj6bYNvp1WtpIARTYRKXs8cszEFnm5Z Jde4K81mFCrSRjIxVGIv55fWuSnviaj7D3F0DMp+Yn9U/pjPTgobN/6rPEpQFr3qCHrX9sO24B6 1coso6XRkQudf8HUB93T7rwP6Zn1KjjuZ/L5IDrRFYYtQ= X-Google-Smtp-Source: AGHT+IFzQjXztABPa+d6GHbYxizlFHE4C9ITCZlSr9sx6kyuFsfSIRo1qbUYH5E0Ghs6mdSry040Nz/4hY0xhg== X-Received: from xllamas.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5070]) (user=cmllamas job=sendgmr) by 2002:a25:d80f:0:b0:dc2:195c:602d with SMTP id p15-20020a25d80f000000b00dc2195c602dmr653308ybg.11.1705614190658; Thu, 18 Jan 2024 13:43:10 -0800 (PST) Date: Thu, 18 Jan 2024 21:42:46 +0000 In-Reply-To: <2024011855-lyricist-marshy-4883@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <2024011855-lyricist-marshy-4883@gregkh> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240118214246.938824-1-cmllamas@google.com> Subject: [PATCH 5.4.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 v5.4. This only works because we check the vma against our cached alloc->vma pointer. Also, unlock via up_read() instead of mmap_read_unlock() as commit d8ed45c5dcd4 is also missing in v5.4.] Signed-off-by: Carlos Llamas --- 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 f766e889d241..fd5e55db44c2 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -953,7 +953,9 @@ enum lru_status binder_alloc_free_page(struct list_head *item, goto err_mmget; if (!down_read_trylock(&mm->mmap_sem)) goto err_down_read_mmap_sem_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); @@ -979,6 +981,8 @@ enum lru_status binder_alloc_free_page(struct list_head *item, mutex_unlock(&alloc->mutex); return LRU_REMOVED_RETRY; +err_invalid_vma: + up_read(&mm->mmap_sem); err_down_read_mmap_sem_failed: mmput_async(mm); err_mmget: -- 2.43.0.429.g432eaa2c6b-goog