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From:   Philipp Stanner <pstanner@redhat.com>
To:     Bjorn Helgaas <bhelgaas@google.com>, Arnd Bergmann <arnd@arndb.de>,
        Hanjun Guo <guohanjun@huawei.com>, NeilBrown <neilb@suse.de>,
        Kent Overstreet <kent.overstreet@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>,
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        Uladzislau Koshchanka <koshchanka@gmail.com>,
        John Sanpe <sanpeqf@gmail.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Philipp Stanner <pstanner@redhat.com>,
        "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        David Gow <davidgow@google.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Shuah Khan <skhan@linuxfoundation.org>,
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        Yury Norov <yury.norov@gmail.com>,
        Jason Baron <jbaron@akamai.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Ben Dooks <ben.dooks@codethink.co.uk>, dakr@redhat.com
Cc:     linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-arch@vger.kernel.org, stable@vger.kernel.org,
        Arnd Bergmann <arnd@kernel.org>
Subject: [PATCH v3 1/5] lib/pci_iomap.c: fix cleanup bugs in pci_iounmap()
Date:   Mon,  4 Dec 2023 13:38:28 +0100
Message-ID: <20231204123834.29247-2-pstanner@redhat.com>
In-Reply-To: <20231204123834.29247-1-pstanner@redhat.com>
References: <20231204123834.29247-1-pstanner@redhat.com>
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pci_iounmap() in lib/pci_iomap.c is supposed to check whether an address
is within ioport-range IF the config specifies that ioports exist. If
so, the port should be unmapped with ioport_unmap(). If not, it's a
generic MMIO address that has to be passed to iounmap().

The bugs are:
  1. ioport_unmap() is missing entirely, so this function will never
     actually unmap a port.
  2. the #ifdef for the ioport-ranges accidentally also guards
     iounmap(), potentially compiling an empty function. This would
     cause the mapping to be leaked.

Implement the missing call to ioport_unmap().

Move the guard so that iounmap() will always be part of the function.

CC: <stable@vger.kernel.org> # v5.15+
Fixes: 316e8d79a095 ("pci_iounmap'2: Electric Boogaloo: try to make sense of it all")
Reported-by: Danilo Krummrich <dakr@redhat.com>
Suggested-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
In case someone wants to look into that and provide patches for kernels
older than v5.15:
Note that this patch only applies to v5.15+ – the leaks, however, are
older. I went through the log briefly and it seems f5810e5c32923 already
contains them in asm-generic/io.h.
---
 lib/pci_iomap.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index ce39ce9f3526..6e144b017c48 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -168,10 +168,12 @@ void pci_iounmap(struct pci_dev *dev, void __iomem *p)
 	uintptr_t start = (uintptr_t) PCI_IOBASE;
 	uintptr_t addr = (uintptr_t) p;
 
-	if (addr >= start && addr < start + IO_SPACE_LIMIT)
+	if (addr >= start && addr < start + IO_SPACE_LIMIT) {
+		ioport_unmap(p);
 		return;
-	iounmap(p);
+	}
 #endif
+	iounmap(p);
 }
 EXPORT_SYMBOL(pci_iounmap);
 
-- 
2.43.0