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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-flakey.c
parent16245bdc9d3e22d1460341a655c8b5288953bc14 (diff)
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-flakey.c')
-rw-r--r--drivers/md/dm-flakey.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index 9721f2ffb1a..5d6c04cceee 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -337,8 +337,8 @@ static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
return error;
}
-static int flakey_status(struct dm_target *ti, status_type_t type,
- unsigned status_flags, char *result, unsigned maxlen)
+static void flakey_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
{
unsigned sz = 0;
struct flakey_c *fc = ti->private;
@@ -368,7 +368,6 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
break;
}
- return 0;
}
static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
@@ -411,7 +410,7 @@ static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_
static struct target_type flakey_target = {
.name = "flakey",
- .version = {1, 3, 0},
+ .version = {1, 3, 1},
.module = THIS_MODULE,
.ctr = flakey_ctr,
.dtr = flakey_dtr,