From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Luis Chamberlain <mcgrof@kernel.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Douglas Anderson <dianders@chromium.org>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Jiri Kosina <jikos@kernel.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        Chris Down <chris@chrisdown.name>,
        Nick Terrell <terrelln@fb.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-modules@vger.kernel.org,
        linux-kernel@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net,
        live-patching@vger.kernel.org, bpf@vger.kernel.org,
        llvm@lists.linux.dev
Cc:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Piotr Gorski <piotrgorski@cachyos.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Stephen Boyd <swboyd@chromium.org>,
        Ira Weiny <ira.weiny@intel.com>
Subject: [PATCH] module/decompress: Never use kunmap() for local un-mappings
Date:   Wed, 15 Mar 2023 13:52:56 +0100
Message-Id: <20230315125256.22772-1-fmdefrancesco@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Use kunmap_local() to unmap pages locally mapped with kmap_local_page().

kunmap_local() must be called on the kernel virtual address returned by
kmap_local_page(), differently from how we use kunmap() which instead
expects the mapped page as its argument.

In module_zstd_decompress() we currently map with kmap_local_page() and
unmap with kunmap(). This breaks the code and so it should be fixed.

Cc: Piotr Gorski <piotrgorski@cachyos.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Fixes: 169a58ad824d ("module/decompress: Support zstd in-kernel decompression")
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 kernel/module/decompress.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
index bb79ac1a6d8f..7ddc87bee274 100644
--- a/kernel/module/decompress.c
+++ b/kernel/module/decompress.c
@@ -267,7 +267,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
 		zstd_dec.size = PAGE_SIZE;
 
 		ret = zstd_decompress_stream(dstream, &zstd_dec, &zstd_buf);
-		kunmap(page);
+		kunmap_local(zstd_dec.dst);
 		retval = zstd_get_error_code(ret);
 		if (retval)
 			break;
-- 
2.39.2