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platform/surface: aggregator_tabletsw: accept zero-padded source-list responses #173

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platform/surface: aggregator_tabletsw: accept zero-padded source-list responses #173

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16 changes: 14 additions & 2 deletions drivers/platform/surface/surface_aggregator_tabletsw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/workqueue.h>

Expand Down Expand Up @@ -328,6 +329,7 @@ MODULE_PARM_DESC(tablet_mode_in_slate_state, "Enable tablet mode in slate device

#define SSAM_EVENT_POS_CID_POSTURE_CHANGED 0x03
#define SSAM_POS_MAX_SOURCES 4
#define SSAM_POS_SOURCE_LIST_PADDING_SIZE sizeof(__le32)

enum ssam_pos_source_id {
SSAM_POS_SOURCE_COVER = 0x00,
Expand All @@ -353,6 +355,7 @@ enum ssam_pos_state_sls {
struct ssam_sources_list {
__le32 count;
__le32 id[SSAM_POS_MAX_SOURCES];
u8 padding[SSAM_POS_SOURCE_LIST_PADDING_SIZE];
} __packed;

static const char *ssam_pos_state_name_cover(struct ssam_tablet_sw *sw, u32 state)
Expand Down Expand Up @@ -477,6 +480,8 @@ static int ssam_pos_get_sources_list(struct ssam_tablet_sw *sw, struct ssam_sour
{
struct ssam_request rqst;
struct ssam_response rsp;
u32 count;
size_t expected;
int status;

rqst.target_category = SSAM_SSH_TC_POS;
Expand All @@ -501,8 +506,15 @@ static int ssam_pos_get_sources_list(struct ssam_tablet_sw *sw, struct ssam_sour
return -EPROTO;
}

/* Make sure 'sources->count' matches with the response length. */
if (get_unaligned_le32(&sources->count) * sizeof(__le32) + sizeof(__le32) != rsp.length) {
count = get_unaligned_le32(&sources->count);
if (count > ARRAY_SIZE(sources->id)) {
dev_err(&sw->sdev->dev, "too many posture sources: %u\n", count);
return -EPROTO;
}

expected = sizeof(sources->count) + count * sizeof(sources->id[0]);
if (rsp.length < expected ||
memchr_inv((u8 *)sources + expected, 0, rsp.length - expected)) {
dev_err(&sw->sdev->dev, "mismatch between number of sources and response size\n");
return -EPROTO;
}
Expand Down