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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: Ben Zhang <benzh@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Ben Zhang 2015-05-21 09:50:34 -07:00 committed by Tony Luck
parent 07239fc854
commit e036bd330d
1 changed files with 28 additions and 12 deletions
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40
fs/pstore/ram.c
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@ -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;
}
}
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))
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);