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authorMikulas Patocka <mpatocka@redhat.com>2013-03-02 02:45:44 +0400
committerAlasdair G Kergon <agk@redhat.com>2013-03-02 02:45:44 +0400
commitfd7c092e711ebab55b2688d3859d95dfd0301f73 (patch)
tree3cc99f96f4a2de8e22347feb86b0ecd5dd7200d0 /drivers/md/dm-mpath.c
parent16245bdc9d3e22d1460341a655c8b5288953bc14 (diff)
downloadlinux-fd7c092e711ebab55b2688d3859d95dfd0301f73.tar.xz
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-mpath.c')
-rw-r--r--drivers/md/dm-mpath.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 573bd04591bf..d267bb5705e9 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1378,8 +1378,8 @@ static void multipath_resume(struct dm_target *ti)
* [priority selector-name num_ps_args [ps_args]*
* num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
*/
-static int multipath_status(struct dm_target *ti, status_type_t type,
- unsigned status_flags, char *result, unsigned maxlen)
+static void multipath_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
{
int sz = 0;
unsigned long flags;
@@ -1485,8 +1485,6 @@ static int multipath_status(struct dm_target *ti, status_type_t type,
}
spin_unlock_irqrestore(&m->lock, flags);
-
- return 0;
}
static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
@@ -1695,7 +1693,7 @@ out:
*---------------------------------------------------------------*/
static struct target_type multipath_target = {
.name = "multipath",
- .version = {1, 5, 0},
+ .version = {1, 5, 1},
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,