From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-9.mta1.migadu.com [95.215.58.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3891A353A86 for ; Tue, 25 Aug 2026 18:17:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787681842; cv=none; b=DUAsyK0zoKHT8TY5NwmR4xYuw+4HOZu6eusSkyaJRTOQPUAeAxnwpk7HkltdDtnqVSgZ89LtIl3Pdf6Lt4OI02caZlDjT1oe5haKdYmVgWNE5ruBHwsEJtQL4LaNw5scvg9dHvwhJPLg47O0d2qZ0i4UXOE5sF/KxVAmYJgC1j0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787681842; c=relaxed/simple; bh=pKWQSQwhloU3UCIEHsjSAI70zbgmQD2DReSgXVQRLss=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=g0ir6pb6ANypk00wAs+mn/i8sN2vsB/b11R/CnMytOLTYDtDgkYDEmzPeH8BLTakBs3WNbAlQpUpX3TGvFkslu9Xp/zEMgkYxmSQOrCB31QxVt7pPReDOSYw7FTzpVizMqfUy5kExgp8XSNEdKdkAVgS8binTp4HIknj2xG0Ens= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=justthetip.ca; spf=pass smtp.mailfrom=justthetip.ca; dkim=pass (2048-bit key) header.d=justthetip.ca header.i=@justthetip.ca header.b=EJ/mOqoZ; arc=none smtp.client-ip=95.215.58.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=justthetip.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=justthetip.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=justthetip.ca header.i=@justthetip.ca header.b="EJ/mOqoZ" X-Envelope-To: linux-wireless@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=pKWQSQwhloU3UCIEHsjSAI70zbgmQD2DReSgXVQRLss=; c=simple/simple; d=justthetip.ca; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787681836; v=1; x=1788286636; b=EJ/mOqoZ+3MOkD16zga+8Vp/045+ISk8lKiwywgT2lvax744TV/6PjPdxT70FPnL61gPofM2 iboyQMF+4T36bLBFEfCpvKxR6MH2hD39JfikYHbih/8yH8s+6yjNrW6PzCkTGzOiHINVPe3oxga 6rFBXSxPZrBdVeYWeGWZxzePEn0gPDi0mQ+Oiq+nRAAmL9eRXKy+PLpgAeYHcEWPGCUOQCq2Lje GdhXSjnp0f/Dnn4u/MHljGWlIe5paNbIVH90OLFNHw00qGO1Tf1EGx1vgXnMOmxXuaZfz20dQfv mhCDAtjzr23pFgoF+ge2vERKlH+XAbuEd0BEoXNfI0duA== X-Envelope-To: linux-wireless@vger.kernel.org Received: from fedora (2001:569:be59:c500:b340:3f2c:4486:21c1) by smtp.migadu.com with ESMTPS id c14991048ca0b0d5; Tue, 25 Aug 2026 18:17:16 +0000 X-Mizu-Trace-ID: c14991048ca0b0d5 X-Migadu-Flow: FLOW_OUT From: Devin Wittmayer To: Felix Fietkau , Lorenzo Bianconi Cc: Klara Modin , Charlie-cy Wu , JB Tsai , Sean Wang , Ryder Lee , Shayne Chen , Matthias Brugger , AngeloGioacchino Del Regno , linux-wireless@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, regressions@lists.linux.dev Subject: [PATCH wireless] wifi: mt76: mt792x: fix NULL dereference in ACPI SAR init during probe Date: Tue, 25 Aug 2026 11:17:12 -0700 Message-ID: <20260825181712.28548-1-lucid_duck@justthetip.ca> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Some laptops carry a MediaTek power table in their firmware, and the driver reads it to set a transmit limit for each frequency range. It only fills in the ranges themselves when it registers the device. The startup step that does this existed already, but it never programmed anything. These two commits made it run a regulatory update instead, which sets the limits on the way through, long before registration. So on a machine that has the table the driver reads through an empty pointer and the interface never appears: BUG: kernel NULL pointer dereference, address: 0000000000000004 RIP: 0010:mt792x_init_acpi_sar_power Call Trace: mt7921_set_tx_sar_pwr mt7921_mcu_regd_update mt7921_regd_update mt7921_run_firmware mt7921e_mcu_init mt7921_init_work Skip it when the ranges are missing. They are applied again once the device is up, which is where they came from before. Reported-by: Klara Modin Closes: https://lore.kernel.org/linux-wireless/aoyxqHYvSuaBeubf@soda.int.kasm.eu/ Fixes: 9b80bd9cab40 ("wifi: mt76: mt7921: add regulatory wiphy self manager support") Fixes: e9f3f1cc133f ("wifi: mt76: mt7925: add regulatory wiphy self manager support") Signed-off-by: Devin Wittmayer --- Reproduced on both chips before sending, an MT7922 and an MT7925, and the fix clears both. Neither machine here ships a vendor power table, so I supplied one through an ACPI override in the initrd. It also wants recent firmware. The June builds do not turn on self-managed regulatory and nothing happens; the builds now in linux-firmware do, and then it dies exactly as reported with no interface at all. Patched, both come up and scan normally, and the injected limits still show through in the power table afterwards, so the skip does not lose them. With that table still in place and the fix absent, backing out the mt7921 commit on its own also boots clean, so the table is not what causes this. drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c b/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c index 946dd7956e4a..b468051fbe68 100644 --- a/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c +++ b/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c @@ -323,7 +323,8 @@ int mt792x_init_acpi_sar_power(struct mt792x_phy *phy, bool set_default) const struct cfg80211_sar_capa *capa = phy->mt76->hw->wiphy->sar_capa; int i; - if (!phy->acpisar || !((struct mt792x_acpi_sar *)phy->acpisar)->dyn) + if (!capa || !phy->acpisar || + !((struct mt792x_acpi_sar *)phy->acpisar)->dyn) return 0; /* When ACPI SAR enabled in HW, we should apply rules for .frp -- 2.55.0