From 3aef021b2df7d8440225a53460c0d34b140297d5 Mon Sep 17 00:00:00 2001 From: Tomas Winkler Date: Tue, 11 Feb 2020 18:05:22 +0200 Subject: 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 Link: https://lore.kernel.org/r/20200211160522.7562-1-tomas.winkler@intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/mei/client.c | 4 ++-- drivers/misc/mei/hw.h | 3 +++ 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c index 1e3edbbacb1e..204d807e755b 100644 --- a/drivers/misc/mei/client.c +++ b/drivers/misc/mei/client.c @@ -1585,7 +1585,7 @@ int mei_cl_irq_write(struct mei_cl *cl, struct mei_cl_cb *cb, goto err; } - hbuf_len = mei_slots2data(hbuf_slots); + hbuf_len = mei_slots2data(hbuf_slots) & MEI_MSG_MAX_LEN_MASK; dr_slots = mei_dma_ring_empty_slots(dev); dr_len = mei_slots2data(dr_slots); @@ -1718,7 +1718,7 @@ ssize_t mei_cl_write(struct mei_cl *cl, struct mei_cl_cb *cb) goto out; } - hbuf_len = mei_slots2data(hbuf_slots); + hbuf_len = mei_slots2data(hbuf_slots) & MEI_MSG_MAX_LEN_MASK; dr_slots = mei_dma_ring_empty_slots(dev); dr_len = mei_slots2data(dr_slots); diff --git a/drivers/misc/mei/hw.h b/drivers/misc/mei/hw.h index d025a5f8317e..8231b6941adf 100644 --- a/drivers/misc/mei/hw.h +++ b/drivers/misc/mei/hw.h @@ -209,6 +209,9 @@ struct mei_msg_hdr { u32 extension[0]; } __packed; +/* The length is up to 9 bits */ +#define MEI_MSG_MAX_LEN_MASK GENMASK(9, 0) + #define MEI_MSG_HDR_MAX 2 struct mei_bus_message { -- cgit v1.2.3