pstore/ram: Strip ramoops header for correct decompression
pstore compression/decompression was added during 3.12.
The ramoops driver prepends a "====timestamp.timestamp-C|D\n"
header to the compressed record before handing it over to pstore
driver which doesn't know about the header. In pstore_decompress(),
the pstore driver reads the first "==" as a zlib header, so the
decompression always fails. For example, this causes the driver
to write /dev/pstore/dmesg-ramoops-0.enc.z instead of
/dev/pstore/dmesg-ramoops-0.
This patch makes the ramoops driver remove the header before
pstore decompression.
Signed-off-by: Ben Zhang <benzh@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 56c67dc..c913151 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -143,25 +143,27 @@
return prz;
}
-static void ramoops_read_kmsg_hdr(char *buffer, struct timespec *time,
+static int ramoops_read_kmsg_hdr(char *buffer, struct timespec *time,
bool *compressed)
{
char data_type;
+ int header_length = 0;
- if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n",
- &time->tv_sec, &time->tv_nsec, &data_type) == 3) {
+ if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n%n", &time->tv_sec,
+ &time->tv_nsec, &data_type, &header_length) == 3) {
if (data_type == 'C')
*compressed = true;
else
*compressed = false;
- } else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu\n",
- &time->tv_sec, &time->tv_nsec) == 2) {
+ } else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu\n%n",
+ &time->tv_sec, &time->tv_nsec, &header_length) == 2) {
*compressed = false;
} else {
time->tv_sec = 0;
time->tv_nsec = 0;
*compressed = false;
}
+ return header_length;
}
static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
@@ -173,6 +175,7 @@
ssize_t ecc_notice_size;
struct ramoops_context *cxt = psi->data;
struct persistent_ram_zone *prz;
+ int header_length;
prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,
cxt->max_dump_cnt, id, type,
@@ -186,7 +189,13 @@
if (!prz)
return 0;
+ if (!persistent_ram_old(prz))
+ return 0;
+
size = persistent_ram_old_size(prz);
+ header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz), time,
+ compressed);
+ size -= header_length;
/* ECC correction notice */
ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
@@ -195,8 +204,7 @@
if (*buf == NULL)
return -ENOMEM;
- memcpy(*buf, persistent_ram_old(prz), size);
- ramoops_read_kmsg_hdr(*buf, time, compressed);
+ memcpy(*buf, (char *)persistent_ram_old(prz) + header_length, size);
persistent_ram_ecc_string(prz, *buf + size, ecc_notice_size + 1);
return size + ecc_notice_size;
