linux-kernel - [PATCH -next] pstore: Avoid size casts for 842 compression

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Date:   Tue, 6 Mar 2018 15:18:24 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Geliang Tang <geliangtang@...il.com>
Cc:     linux-kernel@...r.kernel.org, Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>
Subject: [PATCH -next] pstore: Avoid size casts for 842 compression

Instead of casting, make sure we don't end up with giant values and just
perform regular assignments with unsigned int instead of re-cast size_t.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 fs/pstore/platform.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 19aaefeb052f..df54dd87598a 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -452,27 +452,37 @@ static const struct pstore_zbackend backend_lz4hc = {
 static int compress_842(const void *in, void *out, size_t inlen, size_t outlen)
 {
 	int ret;
+	unsigned int size;
 
-	ret = sw842_compress(in, inlen, out, (unsigned int *)&outlen, workspace);
+	if (outlen > UINT_MAX)
+		return -EIO;
+	size = outlen;
+
+	ret = sw842_compress(in, inlen, out, &size, workspace);
 	if (ret) {
 		pr_err("sw842_compress error; compression failed!\n");
 		return ret;
 	}
 
-	return outlen;
+	return size;
 }
 
 static int decompress_842(void *in, void *out, size_t inlen, size_t outlen)
 {
 	int ret;
+	unsigned int size;
 
-	ret = sw842_decompress(in, inlen, out, (unsigned int *)&outlen);
+	if (outlen > UINT_MAX)
+		return -EIO;
+	size = outlen;
+
+	ret = sw842_decompress(in, inlen, out, &size);
 	if (ret) {
 		pr_err("sw842_decompress error, ret = %d!\n", ret);
 		return ret;
 	}
 
-	return outlen;
+	return size;
 }
 
 static void allocate_842(void)
-- 
2.7.4


-- 
Kees Cook
Pixel Security