mei: limit number of bytes in mei header.
The MEI message header provides only 9 bits for storing the message size, limiting to 511. In theory the host buffer (hbuf) can contain up to 1020 bytes (limited by byte = 255 * 4) With the current hardware and hbuf size 512, this is not a real issue, but as hardening approach we enforce the limit. Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Link: https://lore.kernel.org/r/20200211160522.7562-1-tomas.winkler@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1585,7 +1585,7 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb,
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goto err;
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}
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hbuf_len = mei_slots2data(hbuf_slots);
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hbuf_len = mei_slots2data(hbuf_slots) & MEI_MSG_MAX_LEN_MASK;
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dr_slots = mei_dma_ring_empty_slots(dev);
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dr_len = mei_slots2data(dr_slots);
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@ -1718,7 +1718,7 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb)
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goto out;
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}
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hbuf_len = mei_slots2data(hbuf_slots);
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hbuf_len = mei_slots2data(hbuf_slots) & MEI_MSG_MAX_LEN_MASK;
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dr_slots = mei_dma_ring_empty_slots(dev);
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dr_len = mei_slots2data(dr_slots);
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@ -209,6 +209,9 @@ struct mei_msg_hdr {
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u32 extension[0];
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} __packed;
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/* The length is up to 9 bits */
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#define MEI_MSG_MAX_LEN_MASK GENMASK(9, 0)
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#define MEI_MSG_HDR_MAX 2
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struct mei_bus_message {
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