pstore: Handle zero-sized prz in series

ramoops_pstore_read fails to return the next in a prz
series after first zero-sized entry, not venturing to
the next non-zero entry.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 34ed8f860e23..6150e54eed30 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -164,6 +164,12 @@ static int ramoops_read_kmsg_hdr(char *buffer, struct timespec *time,
         return header_length;
 }
 
+static bool prz_ok(struct persistent_ram_zone *prz)
+{
+        return !!prz && !!(persistent_ram_old_size(prz) +
+                           persistent_ram_ecc_string(prz, NULL, 0));
+}
+
 static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
                                    int *count, struct timespec *time,
                                    char **buf, bool *compressed,
@@ -178,13 +184,13 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
         prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,
                                    cxt->max_dump_cnt, id, type,
                                    PSTORE_TYPE_DMESG, 1);
-        if (!prz)
+        if (!prz_ok(prz))
                 prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,
                                            1, id, type, PSTORE_TYPE_CONSOLE, 0);
-        if (!prz)
+        if (!prz_ok(prz))
                 prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt,
                                            1, id, type, PSTORE_TYPE_FTRACE, 0);
-        if (!prz)
+        if (!prz_ok(prz))
                 return 0;
 
         if (!persistent_ram_old(prz))