[PATCH 1/3] drm/ast: Handle failed I2C initialization gracefully

[Dan Carpenter]

Hi Thomas,

url:    https://github.com/0day-ci/linux/commits/Thomas-Zimmermann/ast-Fix-I2C-corner-cases-wrt-init-cleanup/20211201-233308
base:   6a8f90ec433e2f5de5fc16d7a4839771b7027cc0
config: i386-randconfig-m021-20211203 (https://download.01.org/0day-ci/archive/20211204/202112042126.N4Qr3RiC-lkp@intel.com/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp at intel.com>
Reported-by: Dan Carpenter <dan.carpenter at oracle.com>

smatch warnings:
drivers/gpu/drm/ast/ast_mode.c:1231 ast_get_modes() error: uninitialized symbol 'edid'.
drivers/gpu/drm/ast/ast_mode.c:1232 ast_get_modes() warn: passing freed memory 'edid'

vim +/edid +1231 drivers/gpu/drm/ast/ast_mode.c

312fec1405dd54 Dave Airlie       2012-02-29  1209  static int ast_get_modes(struct drm_connector *connector)
312fec1405dd54 Dave Airlie       2012-02-29  1210  {
312fec1405dd54 Dave Airlie       2012-02-29  1211  	struct ast_connector *ast_connector = to_ast_connector(connector);
fa7dbd7688849d Thomas Zimmermann 2020-06-17  1212  	struct ast_private *ast = to_ast_private(connector->dev);
312fec1405dd54 Dave Airlie       2012-02-29  1213  	struct edid *edid;
                                                        ^^^^^^^^^^^^^^^^^^
312fec1405dd54 Dave Airlie       2012-02-29  1214  	int ret;
83c6620bae3f14 Dave Airlie       2014-03-28  1215  	bool flags = false;
6c9bd4432b2527 Gregory Williams  2021-07-30  1216  
83c6620bae3f14 Dave Airlie       2014-03-28  1217  	if (ast->tx_chip_type == AST_TX_DP501) {
83c6620bae3f14 Dave Airlie       2014-03-28  1218  		ast->dp501_maxclk = 0xff;
83c6620bae3f14 Dave Airlie       2014-03-28  1219  		edid = kmalloc(128, GFP_KERNEL);
83c6620bae3f14 Dave Airlie       2014-03-28  1220  		if (!edid)
83c6620bae3f14 Dave Airlie       2014-03-28  1221  			return -ENOMEM;
312fec1405dd54 Dave Airlie       2012-02-29  1222  
83c6620bae3f14 Dave Airlie       2014-03-28  1223  		flags = ast_dp501_read_edid(connector->dev, (u8 *)edid);
83c6620bae3f14 Dave Airlie       2014-03-28  1224  		if (flags)
83c6620bae3f14 Dave Airlie       2014-03-28  1225  			ast->dp501_maxclk = ast_get_dp501_max_clk(connector->dev);
83c6620bae3f14 Dave Airlie       2014-03-28  1226  		else
83c6620bae3f14 Dave Airlie       2014-03-28  1227  			kfree(edid);
                                                                        ^^^^^^^^^^^

83c6620bae3f14 Dave Airlie       2014-03-28  1228  	}
75bd8f71712a8a Thomas Zimmermann 2021-12-01  1229  	if (!flags && ast_connector->i2c)

If "flags" is false then "edid" is either freed or uninitialized.  So
if "ast_connector->i2c" also is false then that's going to cause
problems.  Hopefully that part of the condition can just be removed?

	if (!flags)
		edid = drm_get_edid(connector, &ast_connector->i2c->adapter);

312fec1405dd54 Dave Airlie       2012-02-29  1230  		edid = drm_get_edid(connector, &ast_connector->i2c->adapter);
312fec1405dd54 Dave Airlie       2012-02-29 @1231  	if (edid) {
c555f02371c338 Daniel Vetter     2018-07-09 @1232  		drm_connector_update_edid_property(&ast_connector->base, edid);
312fec1405dd54 Dave Airlie       2012-02-29  1233  		ret = drm_add_edid_modes(connector, edid);
993dcb05e47e35 Jani Nikula       2012-08-15  1234  		kfree(edid);
312fec1405dd54 Dave Airlie       2012-02-29  1235  		return ret;
6c9bd4432b2527 Gregory Williams  2021-07-30  1236  	}
c555f02371c338 Daniel Vetter     2018-07-09  1237  	drm_connector_update_edid_property(&ast_connector->base, NULL);
312fec1405dd54 Dave Airlie       2012-02-29  1238  	return 0;
312fec1405dd54 Dave Airlie       2012-02-29  1239  }

---
0-DAY CI Kernel Test Service, Intel Corporation
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