2023-11-23 10:05:04

by Kunwu Chan

Subject: [PATCH] drm/i915/display: Fix null pointer dereference in intel_dp_aux_wait_done and intel_dp_aux_xfer

kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure. When "intel_dp->aux.name" is NULL,
these error messages will trigger the null pointer dereference issue.

Signed-off-by: Kunwu Chan <[email protected]>
---
drivers/gpu/drm/i915/display/intel_dp_aux.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index 2e2af71bcd5a..398c9064eb09 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -67,7 +67,7 @@ intel_dp_aux_wait_done(struct intel_dp *intel_dp)
if (ret == -ETIMEDOUT)
drm_err(&i915->drm,
"%s: did not complete or timeout within %ums (status 0x%08x)\n",
- intel_dp->aux.name, timeout_ms, status);
+ intel_dp->aux.name ? intel_dp->aux.name : "", timeout_ms, status);

return status;
}
@@ -302,7 +302,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
if (status != intel_dp->aux_busy_last_status) {
drm_WARN(&i915->drm, 1,
"%s: not started (status 0x%08x)\n",
- intel_dp->aux.name, status);
+ intel_dp->aux.name ? intel_dp->aux.name : "", status);
intel_dp->aux_busy_last_status = status;
}

@@ -362,7 +362,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,

if ((status & DP_AUX_CH_CTL_DONE) == 0) {
drm_err(&i915->drm, "%s: not done (status 0x%08x)\n",
- intel_dp->aux.name, status);
+ intel_dp->aux.name ? intel_dp->aux.name : "", status);
ret = -EBUSY;
goto out;
}
@@ -374,7 +374,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
*/
if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
drm_err(&i915->drm, "%s: receive error (status 0x%08x)\n",
- intel_dp->aux.name, status);
+ intel_dp->aux.name ? intel_dp->aux.name : "", status);
ret = -EIO;
goto out;
}
@@ -385,7 +385,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
*/
if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) {
drm_dbg_kms(&i915->drm, "%s: timeout (status 0x%08x)\n",
- intel_dp->aux.name, status);
+ intel_dp->aux.name ? intel_dp->aux.name : "", status);
ret = -ETIMEDOUT;
goto out;
}
@@ -401,7 +401,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
if (recv_bytes == 0 || recv_bytes > 20) {
drm_dbg_kms(&i915->drm,
"%s: Forbidden recv_bytes = %d on aux transaction\n",
- intel_dp->aux.name, recv_bytes);
+ intel_dp->aux.name ? intel_dp->aux.name : "", recv_bytes);
ret = -EBUSY;
goto out;
}
--
2.34.1

2023-11-23 12:23:35

by Ville Syrjälä

Subject: Re: [PATCH] drm/i915/display: Fix null pointer dereference in intel_dp_aux_wait_done and intel_dp_aux_xfer

On Thu, Nov 23, 2023 at 06:04:31PM +0800, Kunwu Chan wrote:
> kasprintf() returns a pointer to dynamically allocated memory
> which can be NULL upon failure. When "intel_dp->aux.name" is NULL,
> these error messages will trigger the null pointer dereference issue.

How did you reach that conclusion?

>
> Signed-off-by: Kunwu Chan <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_dp_aux.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> index 2e2af71bcd5a..398c9064eb09 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> @@ -67,7 +67,7 @@ intel_dp_aux_wait_done(struct intel_dp *intel_dp)
> if (ret == -ETIMEDOUT)
> drm_err(&i915->drm,
> "%s: did not complete or timeout within %ums (status 0x%08x)\n",
> - intel_dp->aux.name, timeout_ms, status);
> + intel_dp->aux.name ? intel_dp->aux.name : "", timeout_ms, status);
>
> return status;
> }
> @@ -302,7 +302,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> if (status != intel_dp->aux_busy_last_status) {
> drm_WARN(&i915->drm, 1,
> "%s: not started (status 0x%08x)\n",
> - intel_dp->aux.name, status);
> + intel_dp->aux.name ? intel_dp->aux.name : "", status);
> intel_dp->aux_busy_last_status = status;
> }
>
> @@ -362,7 +362,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>
> if ((status & DP_AUX_CH_CTL_DONE) == 0) {
> drm_err(&i915->drm, "%s: not done (status 0x%08x)\n",
> - intel_dp->aux.name, status);
> + intel_dp->aux.name ? intel_dp->aux.name : "", status);
> ret = -EBUSY;
> goto out;
> }
> @@ -374,7 +374,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> */
> if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
> drm_err(&i915->drm, "%s: receive error (status 0x%08x)\n",
> - intel_dp->aux.name, status);
> + intel_dp->aux.name ? intel_dp->aux.name : "", status);
> ret = -EIO;
> goto out;
> }
> @@ -385,7 +385,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> */
> if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) {
> drm_dbg_kms(&i915->drm, "%s: timeout (status 0x%08x)\n",
> - intel_dp->aux.name, status);
> + intel_dp->aux.name ? intel_dp->aux.name : "", status);
> ret = -ETIMEDOUT;
> goto out;
> }
> @@ -401,7 +401,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> if (recv_bytes == 0 || recv_bytes > 20) {
> drm_dbg_kms(&i915->drm,
> "%s: Forbidden recv_bytes = %d on aux transaction\n",
> - intel_dp->aux.name, recv_bytes);
> + intel_dp->aux.name ? intel_dp->aux.name : "", recv_bytes);
> ret = -EBUSY;
> goto out;
> }
> --
> 2.34.1

--
Ville Syrj?l?
Intel