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Commit e036bd33 authored by Ben Zhang's avatar Ben Zhang Committed by Tony Luck
Browse files

pstore/ram: verify ramoops header before saving record 



On some devices the persistent memory contains junk after a cold boot,
and /dev/pstore/dmesg-ramoops-* are created with random data which is
not the result of a kernel crash.

This patch adds a ramoops header check and skips any
persistent_ram_zone that does not have a valid header.

Signed-off-by: default avatarBen Zhang <benzh@chromium.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 07239fc8

fs/pstore/ram.c

+28 −12
Original line number Diff line number Diff line
@@ -186,12 +186,34 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	ssize_t size;

	ssize_t ecc_notice_size;

	struct ramoops_context *cxt = psi->data;

	struct persistent_ram_zone *prz;

	int header_length;

	struct persistent_ram_zone *prz = NULL;

	int header_length = 0;



	/* Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but

	 * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have

	 * valid time stamps, so it is initialized to zero.

	 */

	time->tv_sec = 0;

	time->tv_nsec = 0;

	*compressed = false;



	/* Find the next valid persistent_ram_zone for DMESG */

	while (cxt->dump_read_cnt < cxt->max_dump_cnt && !prz) {

		prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,

					   cxt->max_dump_cnt, id, type,

					   PSTORE_TYPE_DMESG, 1);

		if (!prz_ok(prz))

			continue;

		header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),

						      time, compressed);

		/* Clear and skip this DMESG record if it has no valid header */

		if (!header_length) {

			persistent_ram_free_old(prz);

			persistent_ram_zap(prz);

			prz = NULL;

		}

	}



	if (!prz_ok(prz))

		prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,

					   1, id, type, PSTORE_TYPE_CONSOLE, 0);
@@ -204,13 +226,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, 
	if (!prz_ok(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;

	size = persistent_ram_old_size(prz) - header_length;



	/* ECC correction notice */

	ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);