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HID: steam: Reject short reads

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Steam Controller FEATURE reports encode the size of the message in the
message itself. Previously we were trusting that the size reported matched
the size we actually read, leading to a potential issue with short reads.
Instead, we should actually verify the length of the read.

Fixes: c164d6abf3 ("HID: add driver for Valve Steam Controller")
Reported-by: syzbot+75f3f9bff8c510602d36@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=75f3f9bff8c510602d36

Signed-off-by: Vicki Pfau <vi@endrift.com>
Link: https://syzkaller.appspot.com/bug?extid=75f3f9bff8c510602d36
Signed-off-by: Jiri Kosina <jkosina@suse.com>
This commit is contained in:
Vicki Pfau 2026-07-29 21:12:33 -07:00 committed by Jiri Kosina
parent 9f8ee99f83
commit 33ff7b49c3
1 changed files with 25 additions and 4 deletions
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29
drivers/hid/hid-steam.c
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@ -357,6 +357,13 @@ static int steam_recv_report(struct steam_device *steam,
u8 *buf;
int ret;
/*
* All reports start with a two byte header.
* We must read at least two bytes to get a sensible output.
*/
if (size < 2)
return -EINVAL;
r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
if (!r) {
hid_err(steam->hdev, "No HID_FEATURE_REPORT submitted - nothing to read\n");
@ -380,16 +387,30 @@ static int steam_recv_report(struct steam_device *steam,
buf, hid_report_len(r) + 1,
HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
if (ret > 0) {
ret = min(size, ret - 1);
memcpy(data, buf + 1, ret);
/* Remove the report ID from the return buffer */
ret--;
size = min(size, ret);
memcpy(data, buf + 1, size);
}
kfree(buf);
if (ret < 0)
hid_err(steam->hdev, "%s: error %d\n", __func__, ret);
else
hid_dbg(steam->hdev, "Received report %*ph\n", ret, data);
return ret;
hid_dbg(steam->hdev, "Received report %*ph\n", size, data);
if (ret < 0)
return ret;
if (ret < 2) {
hid_err(steam->hdev, "%s: reply too short\n", __func__);
return -EPROTO;
}
if (ret < data[1] + 2) {
hid_err(steam->hdev, "%s: expected %u bytes, read %i\n",
__func__, data[1] + 2, ret);
return -EPROTO;
}
return size;
}
static int steam_send_report(struct steam_device *steam,