From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D753421EED for ; Mon, 13 Jul 2026 13:19:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783948790; cv=none; b=ehTHkl2EPGwwUnxdAe+hRzAk2uwDueolso3G08AqYllItv9jTN7zaj7+lYkwdGoJTxIPOdihtDGlybLOZRLR0fg4ZEiBgpiCKxGtL0OqqewxiIY+XyGJ0uOIiu06akXs2pwn3Glb7SIz8GOYTZdMl0zngZ+iXDfXywaaIs1UaE8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783948790; c=relaxed/simple; bh=3+1mivJwklpWaK8tyHqywP73/wBdbkwulJ+Xu62QU9Q=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=K7RnYc39ASmWYUaoXKV/mccuDUeVzUyOcXXoRJP5Gwa+UtUX8jDnFZ3rZYF9SOao3And+TlMIEnv6rXAl83Qjaiufb+Ml9aa/Ik5sJriO6psTDMky6+vrm7h4V3rgl52NhnWM84bunpeje63cnP+usebjChR/8CI4scr1fYZ8d4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XQOoSWeS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XQOoSWeS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9749D1F000E9; Mon, 13 Jul 2026 13:19:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783948789; bh=yJKkpIxFaTNbXttvxxWTsyu9670D8e7QgN355iC3Jo4=; h=Subject:To:Cc:From:Date; b=XQOoSWeS1me8Y1oSs0ajVakzqQ9IicHeqcY4ZV9iCmwto5+vc7unM3EzyKLOcwm8J LAlpVrd8TIuVEV2qFaWvv0tkpkUzJxaUd5culbfzH36x0VcG5yg05mQX22Zb3rwgxj 7UrmC9y8RzX5nbrL5vaSU4MzPJ646jb2gKBY9Fdg= Subject: FAILED: patch "[PATCH] binder: fix UAF in binder_free_transaction()" failed to apply to 5.10-stable tree To: cmllamas@google.com,aliceryhl@google.com,gregkh@linuxfoundation.org,stable@kernel.org Cc: From: Date: Mon, 13 Jul 2026 15:10:59 +0200 Message-ID: <2026071359-voyage-hassle-bb34@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x f223d27a546c1e1f48d38fd67760e78f068fe8c4 # git commit -s git send-email --to '' --in-reply-to '2026071359-voyage-hassle-bb34@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From f223d27a546c1e1f48d38fd67760e78f068fe8c4 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Fri, 19 Jun 2026 18:52:31 +0000 Subject: [PATCH] binder: fix UAF in binder_free_transaction() In binder_free_transaction(), the t->to_proc is read under the t->lock. However, once the t->lock is dropped, the to_proc can die in parallel. This leads to a use-after-free error when we attempt to acquire its inner lock right afterwards: ================================================================== BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xe4/0x1a0 Write of size 4 at addr ffff00001125da70 by task B/672 CPU: 20 UID: 0 PID: 672 Comm: B Not tainted 7.1.0-rc6-00284-g8e65320d91cd #4 PREEMPT Hardware name: linux,dummy-virt (DT) Call trace: _raw_spin_lock+0xe4/0x1a0 binder_free_transaction+0x8c/0x320 binder_send_failed_reply+0x21c/0x2f8 binder_thread_release+0x488/0x7e0 binder_ioctl+0x12c0/0x29a0 [...] Allocated by task 675: __kmalloc_cache_noprof+0x174/0x444 binder_open+0x118/0xb70 do_dentry_open+0x374/0x1040 vfs_open+0x58/0x3bc [...] Freed by task 212: __kasan_slab_free+0x58/0x80 kfree+0x1a0/0x4a4 binder_proc_dec_tmpref+0x32c/0x5e0 binder_deferred_func+0xc48/0x104c process_one_work+0x53c/0xbc0 [...] ================================================================== To prevent this, pin the target thread (t->to_thread) to guarantee the target process remains alive. Undelivered transactions without a target thread are already safe, as the target process can only be the current context in those paths. Cc: stable Reported-by: Alice Ryhl Closes: https://lore.kernel.org/all/aikJKVuny_eOivwN@google.com/ Fixes: a370003cc301 ("binder: fix possible UAF when freeing buffer") Signed-off-by: Carlos Llamas Reviewed-by: Alice Ryhl Link: https://patch.msgid.link/20260619185233.2194678-2-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 013e2bfab070..8f2ef1bd539f 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1658,10 +1658,19 @@ static void binder_txn_latency_free(struct binder_transaction *t) static void binder_free_transaction(struct binder_transaction *t) { + struct binder_thread *target_thread; struct binder_proc *target_proc; spin_lock(&t->lock); target_proc = t->to_proc; + target_thread = t->to_thread; + /* + * Pin target_thread to keep target_proc alive. Undelivered + * transactions with !target_thread are safe, as target_proc + * can only be the current context there. + */ + if (target_thread) + atomic_inc(&target_thread->tmp_ref); spin_unlock(&t->lock); if (target_proc) { @@ -1676,6 +1685,10 @@ static void binder_free_transaction(struct binder_transaction *t) t->buffer->transaction = NULL; binder_inner_proc_unlock(target_proc); } + + if (target_thread) + binder_thread_dec_tmpref(target_thread); + if (trace_binder_txn_latency_free_enabled()) binder_txn_latency_free(t); /*