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nvmem: mxs-ocotp read problem

PATCH Stanislav Meduna 2 participants 2 messages Apr 26, 2016

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#0 lore raw

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

drivers/nvmem/mxs-ocotp.c +2 -2
index 8ba19bb..914a4fa 100644
@@ -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;
        }
#1 lore raw

Hi Stano,

Am 26.04.2016 um 13:45 schrieb Stanislav Meduna:

Quoted 5 lines

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.

could you please provide me scenario, so i can test it.

Regards
Stefan

Quoted 28 lines

The following patch seems to fix
the problem

Regards
Stano

drivers/nvmem/mxs-ocotp.c +2 -2
index 8ba19bb..914a4fa 100644
@@ -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;
        }