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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Andrew Murray <andrew.murray@arm.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 139/168] asm-generic: io: Fix ioport_map() for !CONFIG_GENERIC_IOMAP && CONFIG_INDIRECT_PIO
Date:   Mon,  8 Oct 2018 20:31:59 +0200
Message-Id: <20181008175625.318696719@linuxfoundation.org>
In-Reply-To: <20181008175620.043587728@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Murray <andrew.murray@arm.com>

[ Upstream commit 500dd232449e7c07500e713dc6970aa713f8e4f1 ]

The !CONFIG_GENERIC_IOMAP version of ioport_map uses MMIO_UPPER_LIMIT to
prevent users from making I/O accesses outside the expected I/O range -
however it erroneously treats MMIO_UPPER_LIMIT as a mask which is
contradictory to its other users.

The introduction of CONFIG_INDIRECT_PIO, which subtracts an arbitrary
amount from IO_SPACE_LIMIT to form MMIO_UPPER_LIMIT, results in ioport_map
mangling the given port rather than capping it.

We address this by aligning more closely with the CONFIG_GENERIC_IOMAP
implementation of ioport_map by using the comparison operator and
returning NULL where the port exceeds MMIO_UPPER_LIMIT. Though note that
we preserve the existing behavior of masking with IO_SPACE_LIMIT such that
we don't break existing buggy drivers that somehow rely on this masking.

Fixes: 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts")
Reported-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/asm-generic/io.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1026,7 +1026,8 @@ static inline void __iomem *ioremap_wt(p
 #define ioport_map ioport_map
 static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
 {
-	return PCI_IOBASE + (port & MMIO_UPPER_LIMIT);
+	port &= IO_SPACE_LIMIT;
+	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
 }
 #endif