pstore: Fix linking when crypto API disabled

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 a9e297e..36714df 100644 (file)
--- 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. */