dm: fix truncated status strings
Avoid returning a truncated table or status string instead of setting
the DM_BUFFER_FULL_FLAG when the last target of a table fills the
buffer.
When processing a table or status request, the function retrieve_status
calls ti->type->status. If ti->type->status returns non-zero,
retrieve_status assumes that the buffer overflowed and sets
DM_BUFFER_FULL_FLAG.
However, targets don't return non-zero values from their status method
on overflow. Most targets returns always zero.
If a buffer overflow happens in a target that is not the last in the
table, it gets noticed during the next iteration of the loop in
retrieve_status; but if a buffer overflow happens in the last target, it
goes unnoticed and erroneously truncated data is returned.
In the current code, the targets behave in the following way:
* dm-crypt returns -ENOMEM if there is not enough space to store the
key, but it returns 0 on all other overflows.
* dm-thin returns errors from the status method if a disk error happened.
This is incorrect because retrieve_status doesn't check the error
code, it assumes that all non-zero values mean buffer overflow.
* all the other targets always return 0.
This patch changes the ti->type->status function to return void (because
most targets don't use the return code). Overflow is detected in
retrieve_status: if the status method fills up the remaining space
completely, it is assumed that buffer overflow happened.
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 5409607..7a66d73 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2299,8 +2299,8 @@
* <transaction id> <used metadata sectors>/<total metadata sectors>
* <used data sectors>/<total data sectors> <held metadata root>
*/
-static int pool_status(struct dm_target *ti, status_type_t type,
- unsigned status_flags, char *result, unsigned maxlen)
+static void pool_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
{
int r;
unsigned sz = 0;
@@ -2326,32 +2326,41 @@
if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
(void) commit_or_fallback(pool);
- r = dm_pool_get_metadata_transaction_id(pool->pmd,
- &transaction_id);
- if (r)
- return r;
+ r = dm_pool_get_metadata_transaction_id(pool->pmd, &transaction_id);
+ if (r) {
+ DMERR("dm_pool_get_metadata_transaction_id returned %d", r);
+ goto err;
+ }
- r = dm_pool_get_free_metadata_block_count(pool->pmd,
- &nr_free_blocks_metadata);
- if (r)
- return r;
+ r = dm_pool_get_free_metadata_block_count(pool->pmd, &nr_free_blocks_metadata);
+ if (r) {
+ DMERR("dm_pool_get_free_metadata_block_count returned %d", r);
+ goto err;
+ }
r = dm_pool_get_metadata_dev_size(pool->pmd, &nr_blocks_metadata);
- if (r)
- return r;
+ if (r) {
+ DMERR("dm_pool_get_metadata_dev_size returned %d", r);
+ goto err;
+ }
- r = dm_pool_get_free_block_count(pool->pmd,
- &nr_free_blocks_data);
- if (r)
- return r;
+ r = dm_pool_get_free_block_count(pool->pmd, &nr_free_blocks_data);
+ if (r) {
+ DMERR("dm_pool_get_free_block_count returned %d", r);
+ goto err;
+ }
r = dm_pool_get_data_dev_size(pool->pmd, &nr_blocks_data);
- if (r)
- return r;
+ if (r) {
+ DMERR("dm_pool_get_data_dev_size returned %d", r);
+ goto err;
+ }
r = dm_pool_get_metadata_snap(pool->pmd, &held_root);
- if (r)
- return r;
+ if (r) {
+ DMERR("dm_pool_get_metadata_snap returned %d", r);
+ goto err;
+ }
DMEMIT("%llu %llu/%llu %llu/%llu ",
(unsigned long long)transaction_id,
@@ -2388,8 +2397,10 @@
emit_flags(&pt->requested_pf, result, sz, maxlen);
break;
}
+ return;
- return 0;
+err:
+ DMEMIT("Error");
}
static int pool_iterate_devices(struct dm_target *ti,
@@ -2468,7 +2479,7 @@
.name = "thin-pool",
.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
DM_TARGET_IMMUTABLE,
- .version = {1, 6, 0},
+ .version = {1, 6, 1},
.module = THIS_MODULE,
.ctr = pool_ctr,
.dtr = pool_dtr,
@@ -2676,8 +2687,8 @@
/*
* <nr mapped sectors> <highest mapped sector>
*/
-static int thin_status(struct dm_target *ti, status_type_t type,
- unsigned status_flags, char *result, unsigned maxlen)
+static void thin_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
{
int r;
ssize_t sz = 0;
@@ -2687,7 +2698,7 @@
if (get_pool_mode(tc->pool) == PM_FAIL) {
DMEMIT("Fail");
- return 0;
+ return;
}
if (!tc->td)
@@ -2696,12 +2707,16 @@
switch (type) {
case STATUSTYPE_INFO:
r = dm_thin_get_mapped_count(tc->td, &mapped);
- if (r)
- return r;
+ if (r) {
+ DMERR("dm_thin_get_mapped_count returned %d", r);
+ goto err;
+ }
r = dm_thin_get_highest_mapped_block(tc->td, &highest);
- if (r < 0)
- return r;
+ if (r < 0) {
+ DMERR("dm_thin_get_highest_mapped_block returned %d", r);
+ goto err;
+ }
DMEMIT("%llu ", mapped * tc->pool->sectors_per_block);
if (r)
@@ -2721,7 +2736,10 @@
}
}
- return 0;
+ return;
+
+err:
+ DMEMIT("Error");
}
static int thin_iterate_devices(struct dm_target *ti,
@@ -2748,7 +2766,7 @@
static struct target_type thin_target = {
.name = "thin",
- .version = {1, 7, 0},
+ .version = {1, 7, 1},
.module = THIS_MODULE,
.ctr = thin_ctr,
.dtr = thin_dtr,