[PATCH] apparmor: replace decompress_zstd() prototype with its entity

[Tetsuo Handa]

Fix "undefined symbol: decompress_zstd" error caused by decompress_zstd()
being guarded by CONFIG_SECURITY_APPARMOR_EXPORT_BINARY=y.

Reported-by: syzbot+1f14a35d0c73d31555e4 at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1f14a35d0c73d31555e4
Fixes: 17b5758bf35c ("apparmor: Initial support for compressed policies")
Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
---
 security/apparmor/apparmorfs.c | 72 +++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 36 deletions(-)

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 2ae9ab94a5a91..152c7967ff1ba 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -483,7 +483,42 @@ static struct aa_loaddata *aa_simple_write_to_buffer(const char __user *userbuf,
 
 	return data;
 }
-static int decompress_zstd(char *src, size_t slen, char *dst, size_t dlen);
+
+static int decompress_zstd(char *src, size_t slen, char *dst, size_t dlen)
+{
+	if (slen < dlen) {
+		const size_t wksp_len = zstd_dctx_workspace_bound();
+		zstd_dctx *ctx;
+		void *wksp;
+		size_t out_len;
+		int ret = 0;
+
+		wksp = kvzalloc(wksp_len, GFP_KERNEL);
+		if (!wksp) {
+			ret = -ENOMEM;
+			goto cleanup;
+		}
+		ctx = zstd_init_dctx(wksp, wksp_len);
+		if (ctx == NULL) {
+			ret = -ENOMEM;
+			goto cleanup;
+		}
+		out_len = zstd_decompress_dctx(ctx, dst, dlen, src, slen);
+		if (zstd_is_error(out_len)) {
+			ret = -EINVAL;
+			goto cleanup;
+		}
+cleanup:
+		kvfree(wksp);
+		return ret;
+	}
+
+	if (dlen < slen)
+		return -EINVAL;
+	memcpy(dst, src, slen);
+	return 0;
+}
+
 /**
  * aa_get_data_from_compressed - common routine for getting compressed policy
  * from user and get both compressed and uncompressed version.
@@ -1517,41 +1552,6 @@ SEQ_RAWDATA_FOPS(revision);
 SEQ_RAWDATA_FOPS(hash);
 SEQ_RAWDATA_FOPS(compressed_size);
 
-static int decompress_zstd(char *src, size_t slen, char *dst, size_t dlen)
-{
-	if (slen < dlen) {
-		const size_t wksp_len = zstd_dctx_workspace_bound();
-		zstd_dctx *ctx;
-		void *wksp;
-		size_t out_len;
-		int ret = 0;
-
-		wksp = kvzalloc(wksp_len, GFP_KERNEL);
-		if (!wksp) {
-			ret = -ENOMEM;
-			goto cleanup;
-		}
-		ctx = zstd_init_dctx(wksp, wksp_len);
-		if (ctx == NULL) {
-			ret = -ENOMEM;
-			goto cleanup;
-		}
-		out_len = zstd_decompress_dctx(ctx, dst, dlen, src, slen);
-		if (zstd_is_error(out_len)) {
-			ret = -EINVAL;
-			goto cleanup;
-		}
-cleanup:
-		kvfree(wksp);
-		return ret;
-	}
-
-	if (dlen < slen)
-		return -EINVAL;
-	memcpy(dst, src, slen);
-	return 0;
-}
-
 static ssize_t rawdata_read(struct file *file, char __user *buf, size_t size,
 			    loff_t *ppos)
 {
-- 
2.52.0