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authorMikulas Patocka <mpatocka@redhat.com>2013-03-01 22:45:44 +0000
committerAlasdair G Kergon <agk@redhat.com>2013-03-01 22:45:44 +0000
commitfd7c092e711ebab55b2688d3859d95dfd0301f73 (patch)
tree3cc99f96f4a2de8e22347feb86b0ecd5dd7200d0 /drivers/md/dm-delay.c
parent16245bdc9d3e22d1460341a655c8b5288953bc14 (diff)
downloadlinaro-lsk-fd7c092e711ebab55b2688d3859d95dfd0301f73.tar.gz
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>
Diffstat (limited to 'drivers/md/dm-delay.c')
-rw-r--r--drivers/md/dm-delay.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index cc1bd048acb..c0d03b006e4 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -293,8 +293,8 @@ static int delay_map(struct dm_target *ti, struct bio *bio)
return delay_bio(dc, dc->read_delay, bio);
}
-static int delay_status(struct dm_target *ti, status_type_t type,
- unsigned status_flags, char *result, unsigned maxlen)
+static void delay_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
{
struct delay_c *dc = ti->private;
int sz = 0;
@@ -314,8 +314,6 @@ static int delay_status(struct dm_target *ti, status_type_t type,
dc->write_delay);
break;
}
-
- return 0;
}
static int delay_iterate_devices(struct dm_target *ti,
@@ -337,7 +335,7 @@ out:
static struct target_type delay_target = {
.name = "delay",
- .version = {1, 2, 0},
+ .version = {1, 2, 1},
.module = THIS_MODULE,
.ctr = delay_ctr,
.dtr = delay_dtr,