diff options
author | Mikulas Patocka <mpatocka@redhat.com> | 2013-03-02 02:45:44 +0400 |
---|---|---|
committer | Alasdair G Kergon <agk@redhat.com> | 2013-03-02 02:45:44 +0400 |
commit | fd7c092e711ebab55b2688d3859d95dfd0301f73 (patch) | |
tree | 3cc99f96f4a2de8e22347feb86b0ecd5dd7200d0 /include | |
parent | 16245bdc9d3e22d1460341a655c8b5288953bc14 (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 'include')
-rw-r--r-- | include/linux/device-mapper.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index bf6afa2fc432..a5cda3ea6b88 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -68,8 +68,8 @@ typedef void (*dm_postsuspend_fn) (struct dm_target *ti); typedef int (*dm_preresume_fn) (struct dm_target *ti); typedef void (*dm_resume_fn) (struct dm_target *ti); -typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type, - unsigned status_flags, char *result, unsigned maxlen); +typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type, + unsigned status_flags, char *result, unsigned maxlen); typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv); |