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| 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 /drivers/md/dm-snap.c | |
| parent | 16245bdc9d3e22d1460341a655c8b5288953bc14 (diff) | |
| download | linux-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-snap.c')
| -rw-r--r-- | drivers/md/dm-snap.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 10079e07edf4..6e45e3774eab 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1836,8 +1836,8 @@ static void snapshot_merge_resume(struct dm_target *ti) start_merge(s); } -static int snapshot_status(struct dm_target *ti, status_type_t type, - unsigned status_flags, char *result, unsigned maxlen) +static void snapshot_status(struct dm_target *ti, status_type_t type, + unsigned status_flags, char *result, unsigned maxlen) { unsigned sz = 0; struct dm_snapshot *snap = ti->private; @@ -1883,8 +1883,6 @@ static int snapshot_status(struct dm_target *ti, status_type_t type, maxlen - sz); break; } - - return 0; } static int snapshot_iterate_devices(struct dm_target *ti, @@ -2138,8 +2136,8 @@ static void origin_resume(struct dm_target *ti) ti->max_io_len = get_origin_minimum_chunksize(dev->bdev); } -static int origin_status(struct dm_target *ti, status_type_t type, - unsigned status_flags, char *result, unsigned maxlen) +static void origin_status(struct dm_target *ti, status_type_t type, + unsigned status_flags, char *result, unsigned maxlen) { struct dm_dev *dev = ti->private; @@ -2152,8 +2150,6 @@ static int origin_status(struct dm_target *ti, status_type_t type, snprintf(result, maxlen, "%s", dev->name); break; } - - return 0; } static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm, @@ -2180,7 +2176,7 @@ static int origin_iterate_devices(struct dm_target *ti, static struct target_type origin_target = { .name = "snapshot-origin", - .version = {1, 8, 0}, + .version = {1, 8, 1}, .module = THIS_MODULE, .ctr = origin_ctr, .dtr = origin_dtr, @@ -2193,7 +2189,7 @@ static struct target_type origin_target = { static struct target_type snapshot_target = { .name = "snapshot", - .version = {1, 11, 0}, + .version = {1, 11, 1}, .module = THIS_MODULE, .ctr = snapshot_ctr, .dtr = snapshot_dtr, |