mtd: intel-dg: Fix accessing regions before setting nregions

The regions array is counted by nregions, but it's set only after
accessing it:

[] UBSAN: array-index-out-of-bounds in drivers/mtd/devices/mtd_intel_dg.c:750:15
[] index 0 is out of range for type '<unknown> [*]'

Fix it by also fixing an undesired behavior: the loop silently ignores
ENOMEM and continues setting the other entries.

CC: Gustavo A. R. Silva <gustavoars@kernel.org>
CC: Raag Jadav <raag.jadav@intel.com>
Reported-by: Jani Partanen <jiipee@sotapeli.fi>
Closes: https://lore.kernel.org/all/caca6c67-4f1d-49f1-948f-e63b6b937b29@sotapeli.fi
Fixes: ceb5ab3cb646 ("mtd: add driver for intel graphics non-volatile memory device")
Signed-off-by: Lucas De Marchi <demarchi@kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Reviewed-by: Raag Jadav <raag.jadav@intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

diff --git a/drivers/mtd/devices/mtd_intel_dg.c b/drivers/mtd/devices/mtd_intel_dg.c
index 2bab30dcd35fd0cf0e7fea92b277bdb76a475d52..7f751c48a76d4c0d51b171d8528bbbfa9a22298e 100644 (file)
--- a/drivers/mtd/devices/mtd_intel_dg.c
+++ b/drivers/mtd/devices/mtd_intel_dg.c
@@ -770,6 +770,7 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
 
        kref_init(&nvm->refcnt);
        mutex_init(&nvm->lock);
+       nvm->nregions = nregions;
 
        for (n = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
                if (!invm->regions[i].name)
@@ -777,13 +778,15 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
 
                char *name = kasprintf(GFP_KERNEL, "%s.%s",
                                       dev_name(&aux_dev->dev), invm->regions[i].name);
-               if (!name)
-                       continue;
+               if (!name) {
+                       ret = -ENOMEM;
+                       goto err;
+               }
+
                nvm->regions[n].name = name;
                nvm->regions[n].id = i;
                n++;
        }
-       nvm->nregions = n; /* in case where kasprintf fail */
 
        ret = devm_pm_runtime_enable(device);
        if (ret < 0) {