On Tue, 2021-03-23 at 14:04 +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> gcc warns about an sprintf() that uses the same buffer as source
> and destination, which is undefined behavior in C99:
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c: In function 'amdgpu_securedisplay_debugfs_write':
> drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c:141:6: error: 'sprintf' argument 3 overlaps destination object 'i2c_output' [-Werror=restrict]
> 141 | sprintf(i2c_output, "%s 0x%X", i2c_output,
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 142 | securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf[i]);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c:97:7: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
> 97 | char i2c_output[256];
> | ^~~~~~~~~~
>
> Rewrite it to remember the current offset into the buffer instead.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c
> index 834440ab9ff7..69d7f6bff5d4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c
> @@ -136,9 +136,10 @@ static ssize_t amdgpu_securedisplay_debugfs_write(struct file *f, const char __u
> ret = psp_securedisplay_invoke(psp, TA_SECUREDISPLAY_COMMAND__SEND_ROI_CRC);
> if (!ret) {
> if (securedisplay_cmd->status == TA_SECUREDISPLAY_STATUS__SUCCESS) {
> + int pos = 0;
> memset(i2c_output, 0, sizeof(i2c_output));
> for (i = 0; i < TA_SECUREDISPLAY_I2C_BUFFER_SIZE; i++)
> - sprintf(i2c_output, "%s 0x%X", i2c_output,
> + pos += sprintf(i2c_output + pos, " 0x%X",
> securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf[i]);
> dev_info(adev->dev, "SECUREDISPLAY: I2C buffer out put is :%s\n", i2c_output);
Perhaps use a hex output like:
---
drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c
index 9cf856c94f94..25bb34c72d20 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c
@@ -97,13 +97,12 @@ static ssize_t amdgpu_securedisplay_debugfs_write(struct file *f, const char __u
uint32_t op;
int i;
char str[64];
- char i2c_output[256];
int ret;
if (*pos || size > sizeof(str) - 1)
return -EINVAL;
- memset(str, 0, sizeof(str));
+ memset(str, 0, sizeof(str));
ret = copy_from_user(str, buf, size);
if (ret)
return -EFAULT;
@@ -139,11 +138,9 @@ static ssize_t amdgpu_securedisplay_debugfs_write(struct file *f, const char __u
ret = psp_securedisplay_invoke(psp, TA_SECUREDISPLAY_COMMAND__SEND_ROI_CRC);
if (!ret) {
if (securedisplay_cmd->status == TA_SECUREDISPLAY_STATUS__SUCCESS) {
- memset(i2c_output, 0, sizeof(i2c_output));
- for (i = 0; i < TA_SECUREDISPLAY_I2C_BUFFER_SIZE; i++)
- sprintf(i2c_output, "%s 0x%X", i2c_output,
- securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf[i]);
- dev_info(adev->dev, "SECUREDISPLAY: I2C buffer out put is :%s\n", i2c_output);
+ dev_info(adev->dev, "SECUREDISPLAY: I2C buffer output is: %*ph\n",
+ (int)TA_SECUREDISPLAY_I2C_BUFFER_SIZE,
+ securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf);
} else {
psp_securedisplay_parse_resp_status(psp, securedisplay_cmd->status);
}
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