Subject: Coverity: mt7996_hw_queue_read(): Integer handling issues

From: coverity-bot <[email-masked]>
Date: Fri, 2 Dec 2022 14:11:33 -0800

Hello!

This is an experimental semi-automated report about issues detected by
Coverity from a scan of next-20221202 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by commits:

  Thu Dec 1 17:29:14 2022 +0100
    98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")

Coverity reported the following:

*** CID 1527813:  Integer handling issues  (SIGN_EXTENSION)
drivers/net/wireless/mediatek/mt76/mt7996/debugfs.c:460 in mt7996_hw_queue_read()
454     	for (i = 0; i < size; i++) {
455     		u32 ctrl, head, tail, queued;
456
457     		if (val & BIT(map[i].index))
458     			continue;
459
vvv     CID 1527813:  Integer handling issues  (SIGN_EXTENSION)
vvv     Suspicious implicit sign extension: "map[i].qid" with type "u8" (8 bits, unsigned) is promoted in "map[i].qid << 24" to type "int" (32 bits, signed), then sign-extended to type "unsigned long" (64 bits, unsigned).  If "map[i].qid << 24" is greater than 0x7FFFFFFF, the upper bits of the result will all be 1.
460     		ctrl = BIT(31) | (map[i].pid << 10) | (map[i].qid << 24);
461     		mt76_wr(dev, MT_FL_Q0_CTRL, ctrl);
462
463     		head = mt76_get_field(dev, MT_FL_Q2_CTRL,
464     				      GENMASK(11, 0));
465     		tail = mt76_get_field(dev, MT_FL_Q2_CTRL,

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):

Reported-by: coverity-bot <[email-masked]>
Addresses-Coverity-ID: 1527813 ("Integer handling issues")
Fixes: 98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")

Thanks for your attention!

-- 
Coverity-bot