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[ios] Support guarding concurrent reads and writes to Annotations

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Since iOS reads Annotations in-process, this CL updates the iOS
intermediate dump handler to check each Annotation to see if it supports
guarding concurrent reads and writes using ScopedSpinGuard.

For any such Annotation, the in-process dump handler now tries (without
spinning) to obtain the ScopedSpinGuard for the Annotation before
reading its memory.

If the ScopedSpinGuard cannot immediately be obtained, the in-process
dump handler just skips writing the memory of the Annotation to the
intermediate dump. (I'd like to follow up and thread down a Params
object so we can experiment with adding an optional timeout to make
this more reliable.)

Change-Id: Ie6c9849fac94ab89b36364b07aea62326cabe552
Bug: crashpad:437
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/4031730
Commit-Queue: Ben Hamilton <benhamilton@google.com>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
This commit is contained in:
Ben Hamilton 2023-01-31 16:18:47 -07:00 committed by Crashpad LUCI CQ
parent 212b8f6b8c
commit c7d9c710f2
4 changed files with 102 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
client/ios_handler/in_process_intermediate_dump_handler.cc
View File

@ -22,12 +22,15 @@
#include <time.h>
#include <iterator>
#include <optional>
#include "build/build_config.h"
#include "snapshot/snapshot_constants.h"
#include "util/ios/ios_intermediate_dump_writer.h"
#include "util/ios/raw_logging.h"
#include "util/ios/scoped_vm_map.h"
#include "util/ios/scoped_vm_read.h"
#include "util/synchronization/scoped_spin_guard.h"
namespace crashpad {
namespace internal {
@ -1163,6 +1166,13 @@ void InProcessIntermediateDumpHandler::WriteCrashpadAnnotationsList(
IOSIntermediateDumpWriter::ScopedArray annotations_array(
writer, IntermediateDumpKey::kAnnotationObjects);
ScopedVMRead<Annotation> current;
// Use vm_read() to ensure that the linked-list AnnotationList head (which is
// a dummy node of type kInvalid) is valid and copy its memory into a
// newly-allocated buffer.
//
// In the case where the pointer has been clobbered or the memory range is not
// readable, skip reading all the Annotations.
if (!current.Read(annotation_list->head())) {
CRASHPAD_RAW_LOG("Unable to read annotation");
return;
@ -1173,6 +1183,12 @@ void InProcessIntermediateDumpHandler::WriteCrashpadAnnotationsList(
index < kMaxNumberOfAnnotations;
++index) {
ScopedVMRead<Annotation> node;
// Like above, use vm_read() to ensure that the node in the linked list is
// valid and copy its memory into a newly-allocated buffer.
//
// In the case where the pointer has been clobbered or the memory range is
// not readable, skip reading this and all further Annotations.
if (!node.Read(current->link_node())) {
CRASHPAD_RAW_LOG("Unable to read annotation");
return;
@ -1187,6 +1203,36 @@ void InProcessIntermediateDumpHandler::WriteCrashpadAnnotationsList(
continue;
}
// For Annotations which support guarding reads from concurrent writes, map
// their memory read-write using vm_remap(), then declare a ScopedSpinGuard
// which lives for the duration of the read.
ScopedVMMap<Annotation> mapped_node;
std::optional<ScopedSpinGuard> annotation_guard;
if (node->concurrent_access_guard_mode() ==
Annotation::ConcurrentAccessGuardMode::kScopedSpinGuard) {
constexpr vm_prot_t kDesiredProtection = VM_PROT_WRITE | VM_PROT_READ;
if (!mapped_node.Map(node.get()) ||
(mapped_node.CurrentProtection() & kDesiredProtection) !=
kDesiredProtection) {
CRASHPAD_RAW_LOG("Unable to map annotation");
// Skip this annotation rather than giving up entirely, since the linked
// node should still be valid.
continue;
}
// TODO(https://crbug.com/crashpad/438): Pass down a `params` object into
// this method to optionally enable a timeout here.
constexpr uint64_t kTimeoutNanoseconds = 0;
annotation_guard =
mapped_node->TryCreateScopedSpinGuard(kTimeoutNanoseconds);
if (!annotation_guard) {
// This is expected if the process is writing to the Annotation, so
// don't log here and skip the annotation.
continue;
}
}
IOSIntermediateDumpWriter::ScopedArrayMap annotation_map(writer);
WritePropertyCString(writer,
IntermediateDumpKey::kAnnotationName,

1
test/ios/BUILD.gn
View File

@ -70,6 +70,7 @@ source_set("xcuitests") {
deps = [
"../../build:ios_enable_arc",
"../../build:ios_xctest",
"../../client:common",
"../../test/ios/host:app_shared_sources",
"../../third_party/edo",
"../../util",

28
test/ios/crash_type_xctest.mm
View File

@ -15,8 +15,11 @@
#import <XCTest/XCTest.h>
#include <objc/runtime.h>
#include <vector>
#import "Service/Sources/EDOClientService.h"
#include "build/build_config.h"
#include "client/length_delimited_ring_buffer.h"
#import "test/ios/host/cptest_shared_object.h"
#include "util/mach/exception_types.h"
#include "util/mach/mach_extensions.h"
@ -322,6 +325,31 @@
isEqualToString:@"same-name 3"]);
XCTAssertTrue([[dict[@"objects"][2] valueForKeyPath:@"#TEST# one"]
isEqualToString:@"moocow"]);
// Ensure `ring_buffer` is present but not `busy_ring_buffer`.
XCTAssertEqual(1u, [dict[@"ringbuffers"] count]);
NSData* ringBufferNSData =
[dict[@"ringbuffers"][0] valueForKeyPath:@"#TEST# ring_buffer"];
crashpad::RingBufferData ringBufferData;
XCTAssertTrue(ringBufferData.DeserializeFromBuffer(ringBufferNSData.bytes,
ringBufferNSData.length));
crashpad::LengthDelimitedRingBufferReader reader(ringBufferData);
std::vector<uint8_t> ringBufferEntry;
XCTAssertTrue(reader.Pop(ringBufferEntry));
NSString* firstEntry = [[NSString alloc] initWithBytes:ringBufferEntry.data()
length:ringBufferEntry.size()
encoding:NSUTF8StringEncoding];
XCTAssertEqualObjects(firstEntry, @"hello");
ringBufferEntry.clear();
XCTAssertTrue(reader.Pop(ringBufferEntry));
NSString* secondEntry = [[NSString alloc] initWithBytes:ringBufferEntry.data()
length:ringBufferEntry.size()
encoding:NSUTF8StringEncoding];
XCTAssertEqualObjects(secondEntry, @"goodbye");
ringBufferEntry.clear();
XCTAssertFalse(reader.Pop(ringBufferEntry));
}
- (void)testDumpWithoutCrash {

34
test/ios/host/cptest_application_delegate.mm
View File

@ -38,6 +38,7 @@
#include "client/crash_report_database.h"
#include "client/crashpad_client.h"
#include "client/crashpad_info.h"
#include "client/ring_buffer_annotation.h"
#include "client/simple_string_dictionary.h"
#include "client/simulate_crash.h"
#include "snapshot/minidump/process_snapshot_minidump.h"
@ -58,6 +59,9 @@ using Report = crashpad::CrashReportDatabase::Report;
namespace {
constexpr crashpad::Annotation::Type kRingBufferType =
crashpad::Annotation::UserDefinedType(42);
base::FilePath GetDatabaseDir() {
base::FilePath database_dir([NSFileManager.defaultManager
URLsForDirectory:NSDocumentDirectory
@ -251,7 +255,8 @@ UIWindow* GetAnyWindow() {
NSDictionary* dict = @{
@"simplemap" : [@{} mutableCopy],
@"vector" : [@[] mutableCopy],
@"objects" : [@[] mutableCopy]
@"objects" : [@[] mutableCopy],
@"ringbuffers" : [@[] mutableCopy],
};
for (const auto* module : process_snapshot->Modules()) {
for (const auto& kv : module->AnnotationsSimpleMap()) {
@ -262,14 +267,18 @@ UIWindow* GetAnyWindow() {
[dict[@"vector"] addObject:@(annotation.c_str())];
}
for (const auto& annotation : module->AnnotationObjects()) {
if (annotation.type !=
if (annotation.type ==
static_cast<uint16_t>(crashpad::Annotation::Type::kString)) {
continue;
std::string value(
reinterpret_cast<const char*>(annotation.value.data()),
annotation.value.size());
[dict[@"objects"]
addObject:@{@(annotation.name.c_str()) : @(value.c_str())}];
} else if (annotation.type == static_cast<uint16_t>(kRingBufferType)) {
NSData* data = [NSData dataWithBytes:annotation.value.data()
length:annotation.value.size()];
[dict[@"ringbuffers"] addObject:@{@(annotation.name.c_str()) : data}];
}
std::string value(reinterpret_cast<const char*>(annotation.value.data()),
annotation.value.size());
[dict[@"objects"]
addObject:@{@(annotation.name.c_str()) : @(value.c_str())}];
}
}
return [dict passByValue];
@ -418,12 +427,23 @@ UIWindow* GetAnyWindow() {
"#TEST# same-name"};
static crashpad::StringAnnotation<32> test_annotation_four{
"#TEST# same-name"};
static crashpad::RingBufferAnnotation<32> test_ring_buffer_annotation(
kRingBufferType, "#TEST# ring_buffer");
static crashpad::RingBufferAnnotation<32> test_busy_ring_buffer_annotation(
kRingBufferType, "#TEST# busy_ring_buffer");
test_annotation_one.Set("moocow");
test_annotation_two.Set("this will be cleared");
test_annotation_three.Set("same-name 3");
test_annotation_four.Set("same-name 4");
test_annotation_two.Clear();
test_ring_buffer_annotation.Push("hello", 5);
test_ring_buffer_annotation.Push("goodbye", 7);
test_busy_ring_buffer_annotation.Push("busy", 4);
// Take the scoped spin guard on `test_busy_ring_buffer_annotation` to mimic
// an in-flight `Push()` so its contents are not included in the dump.
auto guard = test_busy_ring_buffer_annotation.TryCreateScopedSpinGuard(
/*timeout_nanos=*/0);
abort();
}