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| author | Stefan Haberland <sth@linux.ibm.com> | 2022-09-19 18:49:31 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-09-28 12:11:54 +0300 |
| commit | d3a67c21b18f33c79382084af556557c442f12a6 (patch) | |
| tree | bbe7f32b70415640efc031a38166b5c8e4a347cd | |
| parent | faf0e1b5d82b53752f0bd79cdc23a42f8508441b (diff) | |
| download | linux-d3a67c21b18f33c79382084af556557c442f12a6.tar.xz | |
s390/dasd: fix Oops in dasd_alias_get_start_dev due to missing pavgroup
commit db7ba07108a48c0f95b74fabbfd5d63e924f992d upstream.
Fix Oops in dasd_alias_get_start_dev() function caused by the pavgroup
pointer being NULL.
The pavgroup pointer is checked on the entrance of the function but
without the lcu->lock being held. Therefore there is a race window
between dasd_alias_get_start_dev() and _lcu_update() which sets
pavgroup to NULL with the lcu->lock held.
Fix by checking the pavgroup pointer with lcu->lock held.
Cc: <stable@vger.kernel.org> # 2.6.25+
Fixes: 8e09f21574ea ("[S390] dasd: add hyper PAV support to DASD device driver, part 1")
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Link: https://lore.kernel.org/r/20220919154931.4123002-2-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/s390/block/dasd_alias.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/s390/block/dasd_alias.c b/drivers/s390/block/dasd_alias.c index dc78a523a69f..b6b938aa6615 100644 --- a/drivers/s390/block/dasd_alias.c +++ b/drivers/s390/block/dasd_alias.c @@ -675,12 +675,12 @@ int dasd_alias_remove_device(struct dasd_device *device) struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device) { struct dasd_eckd_private *alias_priv, *private = base_device->private; - struct alias_pav_group *group = private->pavgroup; struct alias_lcu *lcu = private->lcu; struct dasd_device *alias_device; + struct alias_pav_group *group; unsigned long flags; - if (!group || !lcu) + if (!lcu) return NULL; if (lcu->pav == NO_PAV || lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING)) @@ -697,6 +697,11 @@ struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device) } spin_lock_irqsave(&lcu->lock, flags); + group = private->pavgroup; + if (!group) { + spin_unlock_irqrestore(&lcu->lock, flags); + return NULL; + } alias_device = group->next; if (!alias_device) { if (list_empty(&group->aliaslist)) { |