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| author | Douglas Anderson <dianders@chromium.org> | 2023-12-14 12:37:52 -0800 |
|---|---|---|
| committer | Douglas Anderson <dianders@chromium.org> | 2023-12-18 08:44:15 -0800 |
| commit | aca58eac52b88138ab98c814afb389a381725cd7 (patch) | |
| tree | 2d434cceca9bbb1ffa8765a68d2949f3eba8caba /drivers/gpu | |
| parent | 3164c8a70073d43629b4e11e083d3d2798f7750f (diff) | |
| download | lwn-aca58eac52b88138ab98c814afb389a381725cd7.tar.gz lwn-aca58eac52b88138ab98c814afb389a381725cd7.zip | |
drm/bridge: ti-sn65dsi86: Never store more than msg->size bytes in AUX xfer
For aux reads, the value `msg->size` indicates the size of the buffer
provided by `msg->buffer`. We should never in any circumstances write
more bytes to the buffer since it may overflow the buffer.
In the ti-sn65dsi86 driver there is one code path that reads the
transfer length from hardware. Even though it's never been seen to be
a problem, we should make extra sure that the hardware isn't
increasing the length since doing so would cause us to overrun the
buffer.
Fixes: 982f589bde7a ("drm/bridge: ti-sn65dsi86: Update reply on aux failures")
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231214123752.v3.2.I7b83c0f31aeedc6b1dc98c7c741d3e1f94f040f8@changeid
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/bridge/ti-sn65dsi86.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index c45c07840f64..b5464199b633 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -527,6 +527,7 @@ static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux, u32 request_val = AUX_CMD_REQ(msg->request); u8 *buf = msg->buffer; unsigned int len = msg->size; + unsigned int short_len; unsigned int val; int ret; u8 addr_len[SN_AUX_LENGTH_REG + 1 - SN_AUX_ADDR_19_16_REG]; @@ -600,7 +601,8 @@ static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux, } if (val & AUX_IRQ_STATUS_AUX_SHORT) { - ret = regmap_read(pdata->regmap, SN_AUX_LENGTH_REG, &len); + ret = regmap_read(pdata->regmap, SN_AUX_LENGTH_REG, &short_len); + len = min(len, short_len); if (ret) goto exit; } else if (val & AUX_IRQ_STATUS_NAT_I2C_FAIL) { |