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 80E5644CF40; Tue, 16 Jun 2026 16:05:19 +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=1781625920; cv=none; b=XlOVmePSmfvnhQgzLedoxAXPzxr8Gb1EQJ1TFQW50vivZha40Y+UdYPaJDA5auEcQFhPLoSAyYKzoAh6s+qFPRmsBOc477pvBAWf38XLHlHSARyWnISJkNu2AwxLp64IGHN1NjaXr/2SNTfzw8/+Qskb14Sz39pIb93NrHGVDps= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781625920; c=relaxed/simple; bh=uHHM9letECF0rV6HXKsCgGBTcLTiyOe2fCVfOEYvumo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c3hAjpYY3QdmwlEsiMavS13fHPveMoSS0WAqhV5w6YOkmtgCyeyeOUrZUhBI96DJru975tLeAj7h4+oEXcFxrvs7lEPDTQlHSQISeAoWpKbcfHnFwuJyqO4ZAw/cH/FD0YMUOE2T/OMD+RlNHI2qOayC3AiGmyQ/6TpvZvkrnvU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cCGAdSoW; 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="cCGAdSoW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 858591F000E9; Tue, 16 Jun 2026 16:05:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781625919; bh=XlM/CAmNh6HznO+s+TWQoQkCvn5kg59OFvTo6FKpgRE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cCGAdSoWTE/oOtRVK2JyFEEm6lPckQkQHRTqjZsAGFI+mzK4mjEUQJ5K+0zk3nW/j kXWVc3KBo1oPUoZQL2gE65AWl7xLto03Y1gU1oFPafoQeZv+6QP5+tmB1wH0wORqNP dWxIfFrMtXajU53TsGHCjVZ7DNUGC/9rDypc2dRc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhenghang Xiao , Srinivas Kandagatla Subject: [PATCH 6.18 232/325] misc: fastrpc: fix use-after-free race in fastrpc_map_create Date: Tue, 16 Jun 2026 20:30:28 +0530 Message-ID: <20260616145109.964333931@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145057.827196531@linuxfoundation.org> References: <20260616145057.827196531@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhenghang Xiao commit 07ebe87915d8accdaba20c4f88c5ae430fe62fbb upstream. fastrpc_map_lookup returns a raw pointer after releasing fl->lock. The caller fastrpc_map_create then calls fastrpc_map_get (kref_get_unless_zero) on this unprotected pointer. A concurrent MEM_UNMAP can free the map between the lock release and the kref operation, resulting in a use-after-free on the freed slab object. Restore the take_ref parameter to fastrpc_map_lookup so the reference is acquired atomically under fl->lock before the pointer is exposed to the caller. Fixes: 10df039834f8 ("misc: fastrpc: Skip reference for DMA handles") Cc: stable@vger.kernel.org Signed-off-by: Zhenghang Xiao Signed-off-by: Srinivas Kandagatla Link: https://patch.msgid.link/20260530204528.116920-5-srini@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/misc/fastrpc.c | 25 +++++++++++-------------- 1 file changed, 11 insertions(+), 14 deletions(-) --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -362,7 +362,7 @@ static int fastrpc_map_get(struct fastrp static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd, - struct fastrpc_map **ppmap) + struct fastrpc_map **ppmap, bool take_ref) { struct fastrpc_map *map = NULL; struct dma_buf *buf; @@ -377,6 +377,12 @@ static int fastrpc_map_lookup(struct fas if (map->fd != fd || map->buf != buf) continue; + if (take_ref) { + ret = fastrpc_map_get(map); + if (ret) + break; + } + *ppmap = map; ret = 0; break; @@ -891,19 +897,10 @@ get_err: static int fastrpc_map_create(struct fastrpc_user *fl, int fd, u64 len, u32 attr, struct fastrpc_map **ppmap) { - struct fastrpc_session_ctx *sess = fl->sctx; - int err = 0; + if (!fastrpc_map_lookup(fl, fd, ppmap, true)) + return 0; - if (!fastrpc_map_lookup(fl, fd, ppmap)) { - if (!fastrpc_map_get(*ppmap)) - return 0; - dev_dbg(sess->dev, "%s: Failed to get map fd=%d\n", - __func__, fd); - } - - err = fastrpc_map_attach(fl, fd, len, attr, ppmap); - - return err; + return fastrpc_map_attach(fl, fd, len, attr, ppmap); } /* @@ -1173,7 +1170,7 @@ cleanup_fdlist: for (i = 0; i < FASTRPC_MAX_FDLIST; i++) { if (!fdlist[i]) break; - if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap)) + if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap, false)) fastrpc_map_put(mmap); }