From nobody Mon Dec 1 21:30:04 2025 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3E7D12D3ED2 for ; Fri, 28 Nov 2025 07:53:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764316417; cv=none; b=fAmIkL0SD/cYDTX1LR+Mt+rex77/0iyC3HZKxF8Bwq0cOVlJc9rzN8xlqKXEnhxDEzg2N5KwmjWKAfyyO0CNv002caOwLZD+S/iOpP9WxP1ojZXLaK7iGq2AAMpwPc0FCpdUHnhOkB3XVDjV/TSKqlbTNvktk/dhCwp3O8l5iEk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764316417; c=relaxed/simple; bh=E3nfH/wDROWMn76OamRRTz8MKtatR3/6FgQcgzBpJLQ=; h=Date:From:To:Cc:Subject:Message-Id:Mime-Version:Content-Type; b=M8tIPiROv3VdeDDajGrzLNww/Yn/gXDxviW9E7dy49VhjXvfy7q0imUTmbOVMFENWwOo54r6nTHk5S02vsCMl1s1BbGvMzitmIkCzUZHTqLi/6Os4geEzhpPWycYqCpvj0VZl4NssAfUvuoq/qjSZd1gpME4kyWXXIL5eAs7lzU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=vz3OtTks; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="vz3OtTks" Date: Fri, 28 Nov 2025 15:53:23 +0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1764316411; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=DrDbDeCmCMAVuHCDRZI0nQkKgbdOK69ysvHBURvPShc=; b=vz3OtTkszKqQ63ETiH/VtHoCmj1zaSGOmz3veA0/VKrmJzAdbpMiMvJ2vBY9IuQpmuBgxa RsHruUIY44LV0JmLXSkkbLlcso7DHB0LmAQfs04xz8tTyKwfGb8ZBTrltgP+KE9WqbuG3G cmJk+m/mJgw/uMK2nliKz10xhef2xiE= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Tianchu Chen To: arnd@arndb.de, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH] char: applicom: fix NULL pointer dereference in ac_ioctl Message-Id: <20251128155323.a786fde92ebb926cbe96fcb1@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Tianchu Chen Discovered by Atuin - Automated Vulnerability Discovery Engine. In ac_ioctl, the validation of IndexCard and the check for a valid RamIO pointer are skipped when cmd is 6. However, the function unconditionally executes readb(apbs[IndexCard].RamIO + VERS) at the end. If cmd is 6, IndexCard may reference a board that does not exist (where RamIO is NULL), leading to a NULL pointer dereference. Fix this by skipping the readb access when cmd is 6, as this command is a global information query and does not target a specific board context. Signed-off-by: Tianchu Chen Acked-by: Arnd Bergmann --- drivers/char/applicom.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/char/applicom.c b/drivers/char/applicom.c index 9fed9706d..c138c468f 100644 --- a/drivers/char/applicom.c +++ b/drivers/char/applicom.c @@ -835,7 +835,10 @@ static long ac_ioctl(struct file *file, unsigned int c= md, unsigned long arg) ret =3D -ENOTTY; break; } - Dummy =3D readb(apbs[IndexCard].RamIO + VERS); + + if (cmd !=3D 6) + Dummy =3D readb(apbs[IndexCard].RamIO + VERS); + kfree(adgl); mutex_unlock(&ac_mutex); return ret; --=20 2.39.5