s390/dasd: fix error checks in dasd_copy_pair_store()

dasd_add_busid() can return an error via ERR_PTR() if an allocation
fails. However, two callsites in dasd_copy_pair_store() do not check
the result, potentially resulting in a NULL pointer dereference. Fix
this by checking the result with IS_ERR() and returning the error up
the stack.

Fixes: a91ff09d39f9b ("s390/dasd: add copy pair setup")
Signed-off-by: Carlos López <clopez@suse.de>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20240715112434.2111291-3-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 0316c20..6adaeb9 100644 (file)
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -2248,13 +2248,19 @@ static ssize_t dasd_copy_pair_store(struct device *dev,
 
        /* allocate primary devmap if needed */
        prim_devmap = dasd_find_busid(prim_busid);
-       if (IS_ERR(prim_devmap))
+       if (IS_ERR(prim_devmap)) {
                prim_devmap = dasd_add_busid(prim_busid, DASD_FEATURE_DEFAULT);
+               if (IS_ERR(prim_devmap))
+                       return PTR_ERR(prim_devmap);
+       }
 
        /* allocate secondary devmap if needed */
        sec_devmap = dasd_find_busid(sec_busid);
-       if (IS_ERR(sec_devmap))
+       if (IS_ERR(sec_devmap)) {
                sec_devmap = dasd_add_busid(sec_busid, DASD_FEATURE_DEFAULT);
+               if (IS_ERR(sec_devmap))
+                       return PTR_ERR(sec_devmap);
+       }
 
        /* setting copy relation is only allowed for offline secondary */
        if (sec_devmap->device)