ARM: ux500: do not directly dereference __iomem

Sparse reports that calling add_device_randomness() on `uid` is a
violation of address spaces. And indeed the next usage uses readl()
properly, but that was left out when passing it toadd_device_
randomness(). So instead copy the whole thing to the stack first.

Fixes: 4040d10a3d44 ("ARM: ux500: add DB serial number to entropy pool")
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/202210230819.loF90KDh-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20221108123755.207438-1-Jason@zx2c4.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/soc/ux500/ux500-soc-id.c b/drivers/soc/ux500/ux500-soc-id.c
index a9472e0e5d61cfa680239b992149beab86f5b427..27d6e25a0115365d4c9d98e1375ef60fc8210a64 100644 (file)
--- a/drivers/soc/ux500/ux500-soc-id.c
+++ b/drivers/soc/ux500/ux500-soc-id.c
@@ -167,20 +167,18 @@ ATTRIBUTE_GROUPS(ux500_soc);
 static const char *db8500_read_soc_id(struct device_node *backupram)
 {
        void __iomem *base;
-       void __iomem *uid;
        const char *retstr;
+       u32 uid[5];
 
        base = of_iomap(backupram, 0);
        if (!base)
                return NULL;
-       uid = base + 0x1fc0;
+       memcpy_fromio(uid, base + 0x1fc0, sizeof(uid));
 
        /* Throw these device-specific numbers into the entropy pool */
-       add_device_randomness(uid, 0x14);
+       add_device_randomness(uid, sizeof(uid));
        retstr = kasprintf(GFP_KERNEL, "%08x%08x%08x%08x%08x",
-                        readl((u32 *)uid+0),
-                        readl((u32 *)uid+1), readl((u32 *)uid+2),
-                        readl((u32 *)uid+3), readl((u32 *)uid+4));
+                          uid[0], uid[1], uid[2], uid[3], uid[4]);
        iounmap(base);
        return retstr;
 }