The last resource should always be ACPI_RESOURCE_TYPE_END_TAG and we have nsrepair mechanism to ensure that this entry is always there for resource based properties (there are still 2 kinds of properties haven't been fixed yet). If we do not want to rely on this logic, then we may need to use buffer->length and pass this one to the acpi_rs_get_aml_length to avoid potential infinite loop. I'll draft an ACPICA patch to achieve the latter. Thanks and best regards -Lv > -----Original Message----- > From: devel-bounces@xxxxxxxxxx [mailto:devel-bounces@xxxxxxxxxx] On Behalf Of Moore, Robert > Sent: Wednesday, October 23, 2013 5:36 AM > To: Dan Carpenter > Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx > Subject: Re: [Devel] ACPICA: Resource Mgr: Prevent infinite loops in resource walks > > We'll take a look. > Thanks, > Bob > > > > -----Original Message----- > > From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx] > > Sent: Thursday, October 17, 2013 5:29 AM > > To: Moore, Robert > > Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx > > Subject: re: ACPICA: Resource Mgr: Prevent infinite loops in resource > > walks > > > > Hello Bob Moore, > > > > The patch c13085e519e8: "ACPICA: Resource Mgr: Prevent infinite loops in > > resource walks" from Mar 8, 2013 is not beautiful. My static checker > > complains about the loop because: > > "drivers/acpi/acpica/rscalc.c:197 acpi_rs_get_aml_length() > > warn: 'resource' can't be NULL." > > > > drivers/acpi/acpica/rscalc.c > > 195 /* Traverse entire list of internal resource descriptors > > */ > > 196 > > 197 while (resource) { > > ^^^^^^^^ > > > > My static checker is wrong because we use the -fno-strict-overflow to > > prevent GCC from optimizing this check away. But we are looping over a > > list of pointers until our pointer wraps to NULL. In other words we loop > > over all the 2**64 - 1 addresses until we wrap to NULL or we find > > something with an invalid type or something with ->length zero. > > > > I assume the last element in the list always has length zero? If so then > > we could replace "while (resource)" with "while (resource->length)" > > > > 198 > > 199 /* Validate the descriptor type */ > > 200 > > 201 if (resource->type > ACPI_RESOURCE_TYPE_MAX) { > > 202 > > return_ACPI_STATUS(AE_AML_INVALID_RESOURCE_TYPE); > > 203 } > > 204 > > 205 /* Sanity check the length. It must not be zero, > > or we loop forever */ > > 206 > > 207 if (!resource->length) { > > 208 > > return_ACPI_STATUS(AE_AML_BAD_RESOURCE_LENGTH); > > 209 } > > 210 > > 211 /* Get the base size of the (external stream) > > resource descriptor */ > > 212 > > > > regards, > > dan carpenter > > _______________________________________________ > Devel mailing list > Devel@xxxxxxxxxx > https://lists.acpica.org/mailman/listinfo/devel -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
