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>

1 files 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)