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@chromium.org>

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 19aaefe..df54dd8 100644 (file)
--- 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)