powerpc/pseries: Add backward compatibilty to read old kernel oops-log

Older kernels has just length information in their header. Handle it
while reading old kernel oops log from pstore.

Applies on top of powerpc/pseries: Fix buffer overflow when reading from pstore

Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index 893f360..6a5f2b1 100644 (file)
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -720,15 +720,25 @@ static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
 
        if (nvram_type_ids[read_type] == PSTORE_TYPE_DMESG) {
                int length, unzipped_len;
+               size_t hdr_size;
 
                oops_hdr = (struct oops_log_info *)buff;
-               length = oops_hdr->report_length;
+               if (oops_hdr->version < OOPS_HDR_VERSION) {
+                       /* Old format oops header had 2-byte record size */
+                       hdr_size = sizeof(u16);
+                       length = oops_hdr->version;
+                       time->tv_sec = 0;
+                       time->tv_nsec = 0;
+               } else {
+                       hdr_size = sizeof(*oops_hdr);
+                       length = oops_hdr->report_length;
+                       time->tv_sec = oops_hdr->timestamp;
+                       time->tv_nsec = 0;
+               }
                *buf = kmalloc(length, GFP_KERNEL);
                if (*buf == NULL)
                        return -ENOMEM;
-               memcpy(*buf, buff + sizeof(*oops_hdr), length);
-               time->tv_sec = oops_hdr->timestamp;
-               time->tv_nsec = 0;
+               memcpy(*buf, buff + hdr_size, length);
                kfree(buff);
 
                if (err_type == ERR_TYPE_KERNEL_PANIC_GZ) {