From: Matteo Croce <mcroce@linux.microsoft.com>
Subject: pstore: Fix linking when crypto API disabled
Git-commit: fd49e03280e596e54edb93a91bc96170f8e97e4a
Patch-mainline: v5.9
References: jsc#SLE-16304
Acked-by: Jiri Bohac <jbohac@suse.cz>

When building a kernel with CONFIG_PSTORE=y and CONFIG_CRYPTO not set,
a build error happens:

    ld: fs/pstore/platform.o: in function `pstore_dump':
    platform.c:(.text+0x3f9): undefined reference to `crypto_comp_compress'
    ld: fs/pstore/platform.o: in function `pstore_get_backend_records':
    platform.c:(.text+0x784): undefined reference to `crypto_comp_decompress'

This because some pstore code uses crypto_comp_(de)compress regardless
of the CONFIG_CRYPTO status. Fix it by wrapping the (de)compress usage
by IS_ENABLED(CONFIG_PSTORE_COMPRESS)

Signed-off-by: Matteo Croce <mcroce@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20200706234045.9516-1-mcroce@linux.microsoft.com
Fixes: cb3bee0369bc ("pstore: Use crypto compress API")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index a9e297eefdff..36714df37d5d 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -269,6 +269,9 @@ static int pstore_compress(const void *in, void *out,
 {
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION))
+		return -EINVAL;
+
 	ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
 	if (ret) {
 		pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
@@ -668,7 +671,7 @@ static void decompress_record(struct pstore_record *record)
 	int unzipped_len;
 	char *unzipped, *workspace;
 
-	if (!record->compressed)
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION) || !record->compressed)
 		return;
 
 	/* Only PSTORE_TYPE_DMESG support compression. */
-- 
2.28.0