drm/radeon/kms/atom: fix gpio i2c table overrun (v2)

The GPIO_I2C_INFO table does not always have
ATOM_MAX_SUPPORTED_DEVICE entries. Limit
the number of indices to the size of the
table.

Should fix Novell bug 589022.

v2: fix typo

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: Stable <stable@kernel.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_atombios.c b/drivers/gpu/drm/radeon/radeon_atombios.c
index 1fff95505cf5..5673665ff216 100644
--- a/drivers/gpu/drm/radeon/radeon_atombios.c
+++ b/drivers/gpu/drm/radeon/radeon_atombios.c
@@ -69,16 +69,19 @@ static inline struct radeon_i2c_bus_rec radeon_lookup_i2c_gpio(struct radeon_dev
         struct radeon_i2c_bus_rec i2c;
         int index = GetIndexIntoMasterTable(DATA, GPIO_I2C_Info);
         struct _ATOM_GPIO_I2C_INFO *i2c_info;
-        uint16_t data_offset;
-        int i;
+        uint16_t data_offset, size;
+        int i, num_indices;
 
         memset(&i2c, 0, sizeof(struct radeon_i2c_bus_rec));
         i2c.valid = false;
 
-        if (atom_parse_data_header(ctx, index, NULL, NULL, NULL, &data_offset)) {
+        if (atom_parse_data_header(ctx, index, &size, NULL, NULL, &data_offset)) {
                 i2c_info = (struct _ATOM_GPIO_I2C_INFO *)(ctx->bios + data_offset);
 
-                for (i = 0; i < ATOM_MAX_SUPPORTED_DEVICE; i++) {
+                num_indices = (size - sizeof(ATOM_COMMON_TABLE_HEADER)) /
+                        sizeof(ATOM_GPIO_I2C_ASSIGMENT);
+
+                for (i = 0; i < num_indices; i++) {
                         gpio = &i2c_info->asGPIO_Info[i];
 
                         if (gpio->sucI2cId.ucAccess == id) {