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Commit a28726b4 authored by Ben Zhang's avatar Ben Zhang Committed by Tony Luck
Browse files

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: default avatarBen Zhang <benzh@chromium.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 0df1f248

fs/pstore/ram.c

+15 −7
Original line number Diff line number Diff line
@@ -135,25 +135,27 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max, 
	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,
@@ -165,6 +167,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	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,
@@ -178,7 +181,13 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	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);
@@ -187,8 +196,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	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;