llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lldb
Author: David Spickett (DavidSpickett)
<details>
<summary>Changes</summary>
Relates to #<!-- -->161510
(it's not fixing it, it's just making the error not be an unhandled error)
When we fail to attach to a process we see if we can add more information about
why it happened:
```
if (status.GetError() == EPERM) {
// Depending on the value of ptrace_scope, we can return a different
// error that suggests how to fix it.
return AddPtraceScopeNote(status.ToError());
}
```
ToError creates a new error value and leaves the one in `status` unchecked.
`status`'s error is ok because it will be checked by Status' destructor.
The problem happens in `AddPtraceScopeNote`. If we take certain return paths,
this new error, or the one we get when trying to find the ptrace scope, may be
unchecked on destruction when the function returns.
To fix this, in AddPtraceScopeNote, consume any errors that we are not going to
return. Anything returned will be checked by some caller.
Reproducing this failure mode is difficult but it can be faked by calling
AddPtraceScopeNote earlier. Which is what I did to prove the concept of the
problem.
---
Full diff: https://github.com/llvm/llvm-project/pull/161673.diff
1 Files Affected:
- (modified) lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp (+4-1)
``````````diff
diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
index 9c798cb1cc8f2..7d0bca738e2e5 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
@@ -219,7 +219,8 @@ static llvm::Error AddPtraceScopeNote(llvm::Error
original_error) {
Expected<int> ptrace_scope = GetPtraceScope();
if (auto E = ptrace_scope.takeError()) {
Log *log = GetLog(POSIXLog::Process);
- LLDB_LOG(log, "error reading value of ptrace_scope: {0}", E);
+ LLDB_LOG(log, "error reading value of ptrace_scope: {0}",
+ llvm::toString(std::move(E)));
// The original error is probably more interesting than not being able to
// read or interpret ptrace_scope.
@@ -230,6 +231,7 @@ static llvm::Error AddPtraceScopeNote(llvm::Error
original_error) {
switch (*ptrace_scope) {
case 1:
case 2:
+ llvm::consumeError(std::move(original_error));
return llvm::createStringError(
std::error_code(errno, std::generic_category()),
"The current value of ptrace_scope is %d, which can cause ptrace to "
@@ -239,6 +241,7 @@ static llvm::Error AddPtraceScopeNote(llvm::Error
original_error) {
"https://www.kernel.org/doc/Documentation/security/Yama.txt.";,
*ptrace_scope);
case 3:
+ llvm::consumeError(std::move(original_error));
return llvm::createStringError(
std::error_code(errno, std::generic_category()),
"The current value of ptrace_scope is 3, which will cause ptrace to "
``````````
</details>
https://github.com/llvm/llvm-project/pull/161673
_______________________________________________
lldb-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
