i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

The data->block[0] variable comes from user and is a number between
0-255. Without proper check, the variable may be very large to cause
an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.

Fix this bug by checking the value of writelen.

Fixes: f6505fbabc42 ("i2c: add SLIMpro I2C device driver on APM X-Gene platform")
Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Cc: stable@vger.kernel.org
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c b/drivers/i2c/busses/i2c-xgene-slimpro.c
index 63259b3ea5abd7aa43de6b22d0ec7861a47e7489..3538d36368a90b5fcf5f8e18e01826908c2198ec 100644 (file)
--- a/drivers/i2c/busses/i2c-xgene-slimpro.c
+++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
@@ -308,6 +308,9 @@ static int slimpro_i2c_blkwr(struct slimpro_i2c_dev *ctx, u32 chip,
        u32 msg[3];
        int rc;
 
+       if (writelen > I2C_SMBUS_BLOCK_MAX)
+               return -EINVAL;
+
        memcpy(ctx->dma_buffer, data, writelen);
        paddr = dma_map_single(ctx->dev, ctx->dma_buffer, writelen,
                               DMA_TO_DEVICE);