Subject: nvmem: mxs-ocotp read problem

From: [email-masked] (Stanislav Meduna)
Date: Tue, 26 Apr 2016 13:45:35 +0200

Hi,

the mxs_ocotp_read seems to incorrectly iterate through
the memory to be read, resulting in a buffer overflow/off-area
access and sometimes oops. The following patch seems to fix
the problem

Regards
                               Stano

diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
index 8ba19bb..914a4fa 100644
--- a/drivers/nvmem/mxs-ocotp.c
+++ b/drivers/nvmem/mxs-ocotp.c
@@ -94,7 +94,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
        if (ret)
                goto close_banks;

-       while (val_size) {
+       while (val_size >= reg_size) {
                if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
                        /* fill up non-data register */
                        *buf = 0;
@@ -103,7 +103,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
                }

                buf++;
-               val_size--;
+               val_size -= reg_size;
                offset += reg_size;
        }