drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:1177 vmw_translate_mob_ptr() warn: passing zero to 'PTR_ERR'

From: Dan Carpenter
Date: Thu Feb 17 2022 - 08:43:52 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: d567f5db412ed52de0b3b3efca4a451263de6108
commit: 8afa13a0583f94c14607e3041c02f068ac8fb628 drm/vmwgfx: Implement DRIVER_GEM
config: i386-randconfig-m021-20220214 (https://download.01.org/0day-ci/archive/20220215/202202151635.DiGY2FPj-lkp@xxxxxxxxx/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@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

smatch warnings:
drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:1177 vmw_translate_mob_ptr() warn: passing zero to 'PTR_ERR'
drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:1231 vmw_translate_guest_ptr() warn: passing zero to 'PTR_ERR'

vim +/PTR_ERR +1177 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c

ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1163 static int vmw_translate_mob_ptr(struct vmw_private *dev_priv,
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1164 struct vmw_sw_context *sw_context,
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1165 SVGAMobId *id,
f1d34bfd70b1b4 Thomas Hellstrom 2018-06-19 1166 struct vmw_buffer_object **vmw_bo_p)
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1167 {
b139d43dacef68 Thomas Hellstrom 2018-09-26 1168 struct vmw_buffer_object *vmw_bo;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1169 uint32_t handle = *id;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1170 struct vmw_relocation *reloc;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1171 int ret;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1172
b139d43dacef68 Thomas Hellstrom 2018-09-26 1173 vmw_validation_preload_bo(sw_context->ctx);
8afa13a0583f94 Zack Rusin 2021-12-06 1174 vmw_bo = vmw_user_bo_noref_lookup(sw_context->filp, handle);
8afa13a0583f94 Zack Rusin 2021-12-06 1175 if (IS_ERR_OR_NULL(vmw_bo)) {

Originally this was just IS_ERR(vmw_bo) and that's the correct check.
When a function returns both error pointers and NULL the NULL means that
there isn't an error but the feature is optional and has been
deliberately disabled.

vmw_user_bo_noref_lookup() is not optional.

5724f899ed8265 Deepak Rawat 2019-02-11 1176 VMW_DEBUG_USER("Could not find or use MOB buffer.\n");
b139d43dacef68 Thomas Hellstrom 2018-09-26 @1177 return PTR_ERR(vmw_bo);

If vmw_user_bo_noref_lookup() were optional then this returns
PTR_ERR(NULL) which is success. Returning success here leads to a crash
in the caller because *vmw_bo_p is not initialized.

ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1178 }
b139d43dacef68 Thomas Hellstrom 2018-09-26 1179 ret = vmw_validation_add_bo(sw_context->ctx, vmw_bo, true, false);
8afa13a0583f94 Zack Rusin 2021-12-06 1180 ttm_bo_put(&vmw_bo->base);
b139d43dacef68 Thomas Hellstrom 2018-09-26 1181 if (unlikely(ret != 0))
b139d43dacef68 Thomas Hellstrom 2018-09-26 1182 return ret;
b139d43dacef68 Thomas Hellstrom 2018-09-26 1183
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1184 reloc = vmw_validation_mem_alloc(sw_context->ctx, sizeof(*reloc));
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1185 if (!reloc)
b139d43dacef68 Thomas Hellstrom 2018-09-26 1186 return -ENOMEM;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1187
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1188 reloc->mob_loc = id;
9c079b8ce8bf8e Thomas Hellstrom 2018-09-26 1189 reloc->vbo = vmw_bo;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1190
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1191 *vmw_bo_p = vmw_bo;
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1192 list_add_tail(&reloc->head, &sw_context->bo_relocations);
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1193
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1194 return 0;
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1195 }
ddcda24e3bec1d Thomas Hellstrom 2012-11-21 1196
e2fa3a76839ada Thomas Hellstrom 2011-10-04 1197 /**
2cd80dbd35518d Zack Rusin 2021-05-05 1198 * vmw_translate_guest_ptr - Prepare to translate a user-space buffer handle
680360a4d3f695 Deepak Rawat 2019-02-13 1199 * to a valid SVGAGuestPtr
e2fa3a76839ada Thomas Hellstrom 2011-10-04 1200 *
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1201 * @dev_priv: Pointer to a device private structure.
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1202 * @sw_context: The software context used for this command batch validation.
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1203 * @ptr: Pointer to the user-space handle to be translated.
680360a4d3f695 Deepak Rawat 2019-02-13 1204 * @vmw_bo_p: Points to a location that, on successful return will carry a
680360a4d3f695 Deepak Rawat 2019-02-13 1205 * non-reference-counted pointer to the DMA buffer identified by the user-space
680360a4d3f695 Deepak Rawat 2019-02-13 1206 * handle in @id.
e2fa3a76839ada Thomas Hellstrom 2011-10-04 1207 *
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1208 * This function saves information needed to translate a user-space buffer
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1209 * handle to a valid SVGAGuestPtr. The translation does not take place
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1210 * immediately, but during a call to vmw_apply_relocations().
680360a4d3f695 Deepak Rawat 2019-02-13 1211 *
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1212 * This function builds a relocation list and a list of buffers to validate.
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1213 * The former needs to be freed using either vmw_apply_relocations() or
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1214 * vmw_free_relocations(). The latter needs to be freed using
c0951b797e7d0f Thomas Hellstrom 2012-11-20 1215 * vmw_clear_validations.
e2fa3a76839ada Thomas Hellstrom 2011-10-04 1216 */
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1217 static int vmw_translate_guest_ptr(struct vmw_private *dev_priv,
fb1d9738ca053e Jakob Bornecrantz 2009-12-10 1218 struct vmw_sw_context *sw_context,
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1219 SVGAGuestPtr *ptr,
f1d34bfd70b1b4 Thomas Hellstrom 2018-06-19 1220 struct vmw_buffer_object **vmw_bo_p)
fb1d9738ca053e Jakob Bornecrantz 2009-12-10 1221 {
b139d43dacef68 Thomas Hellstrom 2018-09-26 1222 struct vmw_buffer_object *vmw_bo;
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1223 uint32_t handle = ptr->gmrId;
fb1d9738ca053e Jakob Bornecrantz 2009-12-10 1224 struct vmw_relocation *reloc;
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1225 int ret;
fb1d9738ca053e Jakob Bornecrantz 2009-12-10 1226
b139d43dacef68 Thomas Hellstrom 2018-09-26 1227 vmw_validation_preload_bo(sw_context->ctx);
8afa13a0583f94 Zack Rusin 2021-12-06 1228 vmw_bo = vmw_user_bo_noref_lookup(sw_context->filp, handle);
8afa13a0583f94 Zack Rusin 2021-12-06 1229 if (IS_ERR_OR_NULL(vmw_bo)) {

Same.

5724f899ed8265 Deepak Rawat 2019-02-11 1230 VMW_DEBUG_USER("Could not find or use GMR region.\n");
b139d43dacef68 Thomas Hellstrom 2018-09-26 @1231 return PTR_ERR(vmw_bo);
fb1d9738ca053e Jakob Bornecrantz 2009-12-10 1232 }
b139d43dacef68 Thomas Hellstrom 2018-09-26 1233 ret = vmw_validation_add_bo(sw_context->ctx, vmw_bo, false, false);
8afa13a0583f94 Zack Rusin 2021-12-06 1234 ttm_bo_put(&vmw_bo->base);
b139d43dacef68 Thomas Hellstrom 2018-09-26 1235 if (unlikely(ret != 0))
b139d43dacef68 Thomas Hellstrom 2018-09-26 1236 return ret;
b139d43dacef68 Thomas Hellstrom 2018-09-26 1237
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1238 reloc = vmw_validation_mem_alloc(sw_context->ctx, sizeof(*reloc));
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1239 if (!reloc)
b139d43dacef68 Thomas Hellstrom 2018-09-26 1240 return -ENOMEM;
fb1d9738ca053e Jakob Bornecrantz 2009-12-10 1241
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1242 reloc->location = ptr;
9c079b8ce8bf8e Thomas Hellstrom 2018-09-26 1243 reloc->vbo = vmw_bo;
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1244 *vmw_bo_p = vmw_bo;
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1245 list_add_tail(&reloc->head, &sw_context->bo_relocations);
fc18afcf5fb2d8 Thomas Hellstrom 2018-09-26 1246
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1247 return 0;
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1248 }
4e4ddd47774313 Thomas Hellstrom 2010-02-21 1249

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