From 01bd694ac2f682fb8017e16148b928482bc8fa4b Mon Sep 17 00:00:00 2001
From: Qiang Yu <quic_qianyu@quicinc.com>
Date: Mon, 11 Dec 2023 14:42:52 +0800
Subject: [PATCH] bus: mhi: host: Drop chan lock before queuing buffers
Git-commit: 01bd694ac2f682fb8017e16148b928482bc8fa4b
Patch-mainline: v6.8-rc1
References: git-fixes CVE-2023-52493 bsc#1221274
Ensure read and write locks for the channel are not taken in succession by
dropping the read lock from parse_xfer_event() such that a callback given
to client can potentially queue buffers and acquire the write lock in that
process. Any queueing of buffers should be done without channel read lock
acquired as it can result in multiple locks and a soft lockup.
Cc: <stable@vger.kernel.org> # 5.7
Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device")
Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Tested-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1702276972-41296-3-git-send-email-quic_qianyu@quicinc.com
[mani: added fixes tag and cc'ed stable]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/bus/mhi/host/main.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index ad7807e4b523..abb561db9ae1 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -644,6 +644,8 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
mhi_del_ring_element(mhi_cntrl, tre_ring);
local_rp = tre_ring->rp;
+ read_unlock_bh(&mhi_chan->lock);
+
/* notify client */
mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
@@ -669,6 +671,8 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
kfree(buf_info->cb_buf);
}
}
+
+ read_lock_bh(&mhi_chan->lock);
}
break;
} /* CC_EOT */
--
2.35.3