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crash-reporter: add a sanity check for kernel dmesg records 

On some devices, after a cold boot, a junk pstore record
/dev/pstore/dmesg-ramoops-0 is created which is just a chunk
of uninitialized memory containing random bits, and it's not
the result of a kernel crash.

The sanity check scans for the dmesg log level pattern to
avoid creating junk .kcrash files.

BUG=chromium:443764
TEST=platform_KernelErrorPaths with 3.8 and 3.14 kernel;
check no kcrash file is created for random binary ramoops dump
on stumpy.

Change-Id: I83041436cd8e5e0c7c0015c529f462032ce82f30
Signed-off-by: Ben Zhang <benzh@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/242147
Reviewed-by: Olof Johansson <olofj@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
This commit is contained in:
Ben Zhang 2015-01-20 17:26:31 -08:00 committed by ChromeOS Commit Bot
parent 859ee45cd2
commit 1c5533d4cd
2 changed files with 24 additions and 7 deletions
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21
crash_reporter/kernel_collector.cc
View File

@ -89,6 +89,8 @@ bool KernelCollector::ReadRecordToString(std::string *contents,
"====\\d+\\.\\d+\n(.*)",
pcrecpp::RE_Options().set_multiline(true).set_dotall(true));
pcrecpp::RE sanity_check_re("\n<\\d+>\\[\\s*(\\d+\\.\\d+)\\]");
FilePath ramoops_record;
GetRamoopsRecordPath(&ramoops_record, current_record);
if (!base::ReadFileToString(ramoops_record, &record)) {
@ -96,18 +98,27 @@ bool KernelCollector::ReadRecordToString(std::string *contents,
return false;
}
*record_found = true;
*record_found = false;
if (record_re.FullMatch(record, &captured)) {
// Found a match, append it to the content, and remove from pstore.
// Found a ramoops header, so strip the header and append the rest.
contents->append(captured);
} else {
*record_found = true;
} else if (sanity_check_re.PartialMatch(record.substr(0, 1024))) {
// pstore compression has been added since kernel 3.12. In order to
// decompress dmesg correctly, ramoops driver has to strip the header
// before handing over the record to the pstore driver, so we don't
// need to do it here anymore.
// need to do it here anymore. However, the sanity check is needed because
// sometimes a pstore record is just a chunk of uninitialized memory which
// is not the result of a kernel crash. See crbug.com/443764
contents->append(record);
*record_found = true;
} else {
LOG(WARNING) << "Found invalid record at " << ramoops_record.value();
}
base::DeleteFile(ramoops_record, false);
// Remove the record from pstore after it's found.
if (*record_found)
base::DeleteFile(ramoops_record, false);
return true;
}

10
crash_reporter/kernel_collector_test.cc
View File

@ -78,15 +78,21 @@ TEST_F(KernelCollectorTest, LoadPreservedDump) {
std::string dump;
dump.clear();
WriteStringToFile(kcrash_file(), "CrashRecordWithoutRamoopsHeader");
WriteStringToFile(kcrash_file(),
"CrashRecordWithoutRamoopsHeader\n<6>[ 0.078852]");
ASSERT_TRUE(collector_.LoadParameters());
ASSERT_TRUE(collector_.LoadPreservedDump(&dump));
ASSERT_EQ("CrashRecordWithoutRamoopsHeader", dump);
ASSERT_EQ("CrashRecordWithoutRamoopsHeader\n<6>[ 0.078852]", dump);
WriteStringToFile(kcrash_file(), "====1.1\nsomething");
ASSERT_TRUE(collector_.LoadParameters());
ASSERT_TRUE(collector_.LoadPreservedDump(&dump));
ASSERT_EQ("something", dump);
WriteStringToFile(kcrash_file(), "\x01\x02\xfe\xff random blob");
ASSERT_TRUE(collector_.LoadParameters());
ASSERT_FALSE(collector_.LoadPreservedDump(&dump));
ASSERT_EQ("", dump);
}
TEST_F(KernelCollectorTest, EnableMissingKernel) {