From c8f40a0bccefd613748d080147469a4652d6e74c Mon Sep 17 00:00:00 2001 From: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Date: Thu, 10 Aug 2023 10:22:36 +0200 Subject: s390/dcssblk: fix kernel crash with list_add corruption Commit fb08a1908cb1 ("dax: simplify the dax_device <-> gendisk association") introduced new logic for gendisk association, requiring drivers to explicitly call dax_add_host() and dax_remove_host(). For dcssblk driver, some dax_remove_host() calls were missing, e.g. in device remove path. The commit also broke error handling for out_dax case in device add path, resulting in an extra put_device() w/o the previous get_device() in that case. This lead to stale xarray entries after device add / remove cycles. In the case when a previously used struct gendisk pointer (xarray index) would be used again, because blk_alloc_disk() happened to return such a pointer, the xa_insert() in dax_add_host() would fail and go to out_dax, doing the extra put_device() in the error path. In combination with an already flawed error handling in dcssblk (device_register() cleanup), which needs to be addressed in a separate patch, this resulted in a missing device_del() / klist_del(), and eventually in the kernel crash with list_add corruption on a subsequent device_add() / klist_add(). Fix this by adding the missing dax_remove_host() calls, and also move the put_device() in the error path to restore the previous logic. Fixes: fb08a1908cb1 ("dax: simplify the dax_device <-> gendisk association") Cc: <stable@vger.kernel.org> # 5.17+ Acked-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> --- drivers/s390/block/dcssblk.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/s390') diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index 6eafd0a34483..06bcb6c78909 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -412,6 +412,7 @@ removeseg: } list_del(&dev_info->lh); + dax_remove_host(dev_info->gd); kill_dax(dev_info->dax_dev); put_dax(dev_info->dax_dev); del_gendisk(dev_info->gd); @@ -707,9 +708,9 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char goto out; out_dax_host: + put_device(&dev_info->dev); dax_remove_host(dev_info->gd); out_dax: - put_device(&dev_info->dev); kill_dax(dev_info->dax_dev); put_dax(dev_info->dax_dev); put_dev: @@ -789,6 +790,7 @@ dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const ch } list_del(&dev_info->lh); + dax_remove_host(dev_info->gd); kill_dax(dev_info->dax_dev); put_dax(dev_info->dax_dev); del_gendisk(dev_info->gd); -- cgit v1.2.3