From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794046197; b=gYUCnTuc/xzg2eus1Ll7ZfJeNskDMsuDEfbXe7H7lguhkv5HVzs7B72Gw2p/TZY8CQto RrRoIO1OVDoJyM5snNIPU8/ZtaSRqaJ/6Cfr52T5elKaI22bCiwMr5F/9G0G1RpoVk7YC mLgSswTEtOeT6vGcerAcSL449xhVt+pJtWDMPXchfCgjGoPt9TM9VMGxy1nlG5GBodATo gCg8LW4KVmFY85ZePCIAKDN5Ujk/0J4BlL1cJqTNmmlfZdxutxXUqgpp7ryLtVYxahW2P PaXjsOwbPDsxxyU6y9vh24aC/AAcAEPzdHb8794iZlLAcCUIe/SU1LO+gaTaFYqHZjA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046197; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=po/+zt8gu6f8jyQIWPWKv9Inr5mVE8hfkFfL4vVErXE=; b=fcRnTM2YpzYEwAXD6C0Cws7GS8xYA+4LwXQ4JI/XhvDFFeOfmpSf7VC7j4vb2lnO0Fgx okbik4zdZRs0MnHG01jvuIcQZYjm5+VGHozDYPrMJfAf9nnEkwk54pXxVBCOdDYNDGAV0 H/vS88wpfHzj+vhJ19nFJIQYKLaeIuyKOkkt5INx/xIg+7OQW+h1+8mPymZnq8+99GVao CflHmVQDEgOo3drYbQNZdthXEk09UyygFkwC2PwH+QnqPrNigPf1DoCyTQN07Ln8wpRJ6 QViaHKVo/iOkuLV1diNVMAakPLBTB226pdRg/ldraqEW0W3LUwIVKtBv3899ZrHZSpQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="I8M/w4LE"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 60C89606A32D for ; Sat, 7 Nov 2026 10:09:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=I8M/w4LE Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68CBA1F0089F; Sat, 7 Nov 2026 10:09:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046197; bh=po/+zt8gu6f8jyQIWPWKv9Inr5mVE8hfkFfL4vVErXE=; h=From:To:Cc:Subject:Date; b=I8M/w4LEX2dBeenJlPq05z1/kcedhiEpi2r6wSIGyarawDyMJocf/iwJpd9ASvfMI Mx2KNndGitiF3hpnH0K5F74iLL73bLroeGltiVmu+7P+fWl2R0mEXDzj/NcpbUfN+i +hb3MpNqiiUxa6hPgYHUtUkwhbDAJLjhTtat1D4d2+KA+YYKNoDqETCE/1gJbA7BVo gcFHrWXmxdbFpwB3Oavt1gU3/WTmCSNyEpYqVu1vRp3qnJVd4LhyDRKvzSwKw3OGzm KAvUv4p0z3FMLyKbQY+/9Peq29nBAjuLMkruzMwxbB3VxDxeKLE5TR2HlQ+7f3CLXc x4DgplvABuVFw== From: Sasha Levin To: gyf161023@gmail.com, ekansh.gupta@oss.qualcomm.com, srini@kernel.org, gregkh@linuxfoundation.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] misc: fastrpc: fix double-free in fastrpc_map_attach() error path" failed to apply to 6.18-stable tree Date: Sat, 7 Nov 2026 05:09:55 -0500 Message-ID: <20261107050955-failed-6.18-09fa66ec1b48@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x 09fa66ec1b4896ab841da085ca58b6433f28f07f # git commit -s git send-email --to '' --in-reply-to '20261107050955-failed-6.18-09fa66ec1b48@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 09fa66ec1b4896ab841da085ca58b6433f28f07f Mon Sep 17 00:00:00 2001 From: Yifei Gao Date: Fri, 2 Oct 2026 11:12:19 +0100 Subject: [PATCH] misc: fastrpc: fix double-free in fastrpc_map_attach() error path map->table is assigned right after dma_buf_map_attachment_unlocked() succeeds. The two failure checks that follow, the len > map->size test and, where subsystem VMIDs are configured, a failed qcom_scm_assign_mem(), jump to map_err with map->table already set. map_err manually calls dma_buf_detach() and dma_buf_put() and then falls through to fastrpc_map_put(). Since that change the error path tail is fastrpc_map_put() -> fastrpc_free_map(), and fastrpc_free_map() already unmaps, detaches and puts the dma-buf whenever map->table is set. The two operations therefore run twice: the second dma_buf_put() drops an extra reference on map->buf, and dma_buf_unmap_attachment_unlocked() dereferences the map->attach already freed by the manual dma_buf_detach(). kref_init() sets the refcount to 1 with no intervening get, so the final fastrpc_map_put() frees the map synchronously and the redundant cleanup is deterministic. The len > map->size branch is reachable by an unprivileged process via FASTRPC_IOCTL_MEM_MAP with an fd whose dma-buf is smaller than the requested length, before any DSP invocation. Route both map->table-is-set failure branches to get_err instead of map_err, so fastrpc_free_map() is the single owner of the unmap/detach/put sequence. map_err is retained for the dma_buf_map_attachment_unlocked() failure, which is reached with map->table still NULL and an attachment that fastrpc_free_map() will not clean up, so its dma_buf_detach()/dma_buf_put() must still run manually. Fixes: 334f1a1cbe03 ("misc: fastrpc: Use fastrpc_map_put in fastrpc_map_create on fail") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Yifei Gao Reviewed-by: Ekansh Gupta Signed-off-by: Srinivas Kandagatla Link: https://patch.msgid.link/20261002101220.1084101-2-srinivas.kandagatla@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/fastrpc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 53ad9a3f10699..904f538f0dd0e 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -927,7 +927,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd, dev_dbg(sess->dev, "Bad size passed len 0x%llx map size 0x%llx\n", len, map->size); err = -EINVAL; - goto map_err; + goto get_err; } map->va = sg_virt(map->table->sgl); map->len = len; @@ -950,7 +950,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd, dev_err(sess->dev, "Failed to assign memory with dma_addr %pad size 0x%llx err %d\n", &map->dma_addr, map->len, err); - goto map_err; + goto get_err; } } spin_lock(&fl->lock); -- 2.53.0