clayborg created this revision.
clayborg added reviewers: labath, aprantl.
Prior to this fix, ELF files might contain PT_LOAD program headers that had a
valid p_vaddr, and a valid file p_offset, but the p_filesz would be zero. For
example in
llvm-project/lldb/test/testcases/functionalities/postmortem/elf-core/thread_crash/linux-i386.core
we see:
Program Headers:
Index p_type p_flags p_offset p_vaddr
p_paddr p_filesz p_memsz p_align
======= ---------------- ---------- ------------------ ------------------
------------------ ------------------ ------------------ ------------------
[ 0] PT_NOTE 0x00000000 0x0000000000000474 0x0000000000000000
0x0000000000000000 0x0000000000001940 0x0000000000000000 0x0000000000000000
[ 1] PT_LOAD 0x00000005 0x0000000000002000 0x0000000008048000
0x0000000000000000 0x0000000000000000 0x0000000000003000 0x0000000000001000
[ 2] PT_LOAD 0x00000004 0x0000000000002000 0x000000000804b000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 3] PT_LOAD 0x00000006 0x0000000000002000 0x000000000804c000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 4] PT_LOAD 0x00000006 0x0000000000002000 0x0000000009036000
0x0000000000000000 0x0000000000000000 0x0000000000025000 0x0000000000001000
[ 5] PT_LOAD 0x00000000 0x0000000000002000 0x00000000f63a1000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 6] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f63a2000
0x0000000000000000 0x0000000000000000 0x0000000000800000 0x0000000000001000
[ 7] PT_LOAD 0x00000000 0x0000000000002000 0x00000000f6ba2000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 8] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f6ba3000
0x0000000000000000 0x0000000000000000 0x0000000000804000 0x0000000000001000
[ 9] PT_LOAD 0x00000005 0x0000000000002000 0x00000000f73a7000
0x0000000000000000 0x0000000000000000 0x00000000001b1000 0x0000000000001000
[ 10] PT_LOAD 0x00000004 0x0000000000002000 0x00000000f7558000
0x0000000000000000 0x0000000000000000 0x0000000000002000 0x0000000000001000
[ 11] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f755a000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 12] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f755b000
0x0000000000000000 0x0000000000000000 0x0000000000003000 0x0000000000001000
[ 13] PT_LOAD 0x00000005 0x0000000000002000 0x00000000f755e000
0x0000000000000000 0x0000000000000000 0x0000000000019000 0x0000000000001000
[ 14] PT_LOAD 0x00000004 0x0000000000002000 0x00000000f7577000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 15] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f7578000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 16] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f7579000
0x0000000000000000 0x0000000000000000 0x0000000000002000 0x0000000000001000
[ 17] PT_LOAD 0x00000005 0x0000000000002000 0x00000000f757b000
0x0000000000000000 0x0000000000000000 0x000000000001c000 0x0000000000001000
[ 18] PT_LOAD 0x00000004 0x0000000000002000 0x00000000f7597000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 19] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f7598000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 20] PT_LOAD 0x00000005 0x0000000000002000 0x00000000f7599000
0x0000000000000000 0x0000000000000000 0x0000000000053000 0x0000000000001000
[ 21] PT_LOAD 0x00000004 0x0000000000002000 0x00000000f75ec000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 22] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f75ed000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 23] PT_LOAD 0x00000005 0x0000000000002000 0x00000000f75ee000
0x0000000000000000 0x0000000000000000 0x0000000000176000 0x0000000000001000
[ 24] PT_LOAD 0x00000004 0x0000000000002000 0x00000000f7764000
0x0000000000000000 0x0000000000000000 0x0000000000006000 0x0000000000001000
[ 25] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f776a000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 26] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f776b000
0x0000000000000000 0x0000000000000000 0x0000000000003000 0x0000000000001000
[ 27] PT_LOAD 0x00000006 0x0000000000002000 0x00000000f778a000
0x0000000000000000 0x0000000000000000 0x0000000000002000 0x0000000000001000
[ 28] PT_LOAD 0x00000004 0x0000000000002000 0x00000000f778c000
0x0000000000000000 0x0000000000002000 0x0000000000002000 0x0000000000001000
[ 29] PT_LOAD 0x00000005 0x0000000000004000 0x00000000f778e000
0x0000000000000000 0x0000000000002000 0x0000000000002000 0x0000000000001000
[ 30] PT_LOAD 0x00000005 0x0000000000006000 0x00000000f7790000
0x0000000000000000 0x0000000000000000 0x0000000000022000 0x0000000000001000
[ 31] PT_LOAD 0x00000004 0x0000000000006000 0x00000000f77b3000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 32] PT_LOAD 0x00000006 0x0000000000006000 0x00000000f77b4000
0x0000000000000000 0x0000000000000000 0x0000000000001000 0x0000000000001000
[ 33] PT_LOAD 0x00000006 0x0000000000006000 0x00000000ffa25000
0x0000000000000000 0x0000000000000000 0x0000000000022000 0x0000000000001000
Prior to this fix if users tried to read memory from one of these addresses
like 0x8048000, they would end up incorrectly reading from the next memory
region that actually had a p_filesz which would be 0x00000000f778c000 in this
case. This fix correctly doesn't include program headers with zero p_filesz in
the ProcessELFCore::m_core_aranges that is used to read memory. I found two
cores files that have this same issue and added tests.
https://reviews.llvm.org/D67370
Files:
lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
Index: lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
===================================================================
--- lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
+++ lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
@@ -118,16 +118,20 @@
FileRange file_range(header.p_offset, header.p_filesz);
VMRangeToFileOffset::Entry range_entry(addr, header.p_memsz, file_range);
- VMRangeToFileOffset::Entry *last_entry = m_core_aranges.Back();
- if (last_entry && last_entry->GetRangeEnd() == range_entry.GetRangeBase() &&
- last_entry->data.GetRangeEnd() == range_entry.data.GetRangeBase() &&
- last_entry->GetByteSize() == last_entry->data.GetByteSize()) {
- last_entry->SetRangeEnd(range_entry.GetRangeEnd());
- last_entry->data.SetRangeEnd(range_entry.data.GetRangeEnd());
- } else {
- m_core_aranges.Append(range_entry);
+ // Only add to m_core_aranges if the file size is non zero. Some core files
+ // have PT_LOAD segments for all address ranges, but set f_filesz to zero for
+ // the .text sections since they can be retrieved from the object files.
+ if (header.p_filesz > 0) {
+ VMRangeToFileOffset::Entry *last_entry = m_core_aranges.Back();
+ if (last_entry && last_entry->GetRangeEnd() == range_entry.GetRangeBase()
&&
+ last_entry->data.GetRangeEnd() == range_entry.data.GetRangeBase() &&
+ last_entry->GetByteSize() == last_entry->data.GetByteSize()) {
+ last_entry->SetRangeEnd(range_entry.GetRangeEnd());
+ last_entry->data.SetRangeEnd(range_entry.data.GetRangeEnd());
+ } else {
+ m_core_aranges.Append(range_entry);
+ }
}
-
// Keep a separate map of permissions that that isn't coalesced so all ranges
// are maintained.
const uint32_t permissions =
Index:
lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
===================================================================
---
lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
+++
lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
@@ -51,6 +51,17 @@
self.assertEqual(process.GetProcessID(), pid)
for thread in process:
+ # Verify that if we try to read memory from a PT_LOAD that has
+ # p_filesz of zero that we don't get bytes from the next section
+ # that actually did have bytes. The addresses below were found by
+ # dumping the program headers of linux-i386.core and
+ # linux-x86_64.core and verifying that they had a p_filesz of zero.
+ mem_err = lldb.SBError()
+ if process.GetAddressByteSize() == 4:
+ bytes_read = process.ReadMemory(0x8048000, 4, mem_err)
+ else:
+ bytes_read = process.ReadMemory(0x400000, 4, mem_err)
+ self.assertEqual(bytes_read, None)
reason = thread.GetStopReason()
if( thread.GetThreadID() == tid ):
self.assertEqual(reason, lldb.eStopReasonSignal)
Index: lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
===================================================================
--- lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
+++ lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
@@ -118,16 +118,20 @@
FileRange file_range(header.p_offset, header.p_filesz);
VMRangeToFileOffset::Entry range_entry(addr, header.p_memsz, file_range);
- VMRangeToFileOffset::Entry *last_entry = m_core_aranges.Back();
- if (last_entry && last_entry->GetRangeEnd() == range_entry.GetRangeBase() &&
- last_entry->data.GetRangeEnd() == range_entry.data.GetRangeBase() &&
- last_entry->GetByteSize() == last_entry->data.GetByteSize()) {
- last_entry->SetRangeEnd(range_entry.GetRangeEnd());
- last_entry->data.SetRangeEnd(range_entry.data.GetRangeEnd());
- } else {
- m_core_aranges.Append(range_entry);
+ // Only add to m_core_aranges if the file size is non zero. Some core files
+ // have PT_LOAD segments for all address ranges, but set f_filesz to zero for
+ // the .text sections since they can be retrieved from the object files.
+ if (header.p_filesz > 0) {
+ VMRangeToFileOffset::Entry *last_entry = m_core_aranges.Back();
+ if (last_entry && last_entry->GetRangeEnd() == range_entry.GetRangeBase() &&
+ last_entry->data.GetRangeEnd() == range_entry.data.GetRangeBase() &&
+ last_entry->GetByteSize() == last_entry->data.GetByteSize()) {
+ last_entry->SetRangeEnd(range_entry.GetRangeEnd());
+ last_entry->data.SetRangeEnd(range_entry.data.GetRangeEnd());
+ } else {
+ m_core_aranges.Append(range_entry);
+ }
}
-
// Keep a separate map of permissions that that isn't coalesced so all ranges
// are maintained.
const uint32_t permissions =
Index: lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
+++ lldb/packages/Python/lldbsuite/test/functionalities/postmortem/elf-core/thread_crash/TestLinuxCoreThreads.py
@@ -51,6 +51,17 @@
self.assertEqual(process.GetProcessID(), pid)
for thread in process:
+ # Verify that if we try to read memory from a PT_LOAD that has
+ # p_filesz of zero that we don't get bytes from the next section
+ # that actually did have bytes. The addresses below were found by
+ # dumping the program headers of linux-i386.core and
+ # linux-x86_64.core and verifying that they had a p_filesz of zero.
+ mem_err = lldb.SBError()
+ if process.GetAddressByteSize() == 4:
+ bytes_read = process.ReadMemory(0x8048000, 4, mem_err)
+ else:
+ bytes_read = process.ReadMemory(0x400000, 4, mem_err)
+ self.assertEqual(bytes_read, None)
reason = thread.GetStopReason()
if( thread.GetThreadID() == tid ):
self.assertEqual(reason, lldb.eStopReasonSignal)
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