Strip ARM64 TBI tag byte from addresses before pread on /proc/<pid>/mem by steveisok · Pull Request #124709 · dotnet/runtime

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

steveisok · 2026-02-21T19:49:07Z

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc//mem treats the offset as a file position where TBI does not apply, causing EINVAL.

Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions.

See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

dotnet-policy-service · 2026-02-21T19:50:14Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This pull request addresses an issue with Android's scudo heap allocator, which uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers. When reading process memory via pread on /proc/<pid>/mem, the kernel treats the offset as a file position rather than a virtual address, causing EINVAL errors for TBI-tagged pointers. The fix strips the top byte from addresses before calling pread.

Changes:

Added TBI tag byte stripping in PAL_ReadProcessMemory for non-Apple platforms
Added TBI tag byte stripping in createdump's ReadProcessMemory before pread calls
Comprehensive comments explaining the Android scudo allocator issue and future-proofing for ARM MTE

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/pal/src/debug/debug.cpp	Strips TBI tag byte from addresses before pread in PAL_ReadProcessMemory for non-Apple platforms
src/coreclr/debug/createdump/crashinfounix.cpp	Strips TBI tag byte from addresses before pread in crash dump memory reading, guarded by TARGET_ARM64

steveisok · 2026-02-24T11:56:09Z

/ba-g Known issues and generic unrelated timeouts

…em (dotnet#124709) Android's scudo heap allocator uses ARM64 Top-Byte Ignore (TBI) to tag heap pointers with a non-zero top byte (e.g., 0xB4). While the CPU ignores this byte during memory access, pread on /proc/<pid>/mem treats the offset as a file position where TBI does not apply, causing EINVAL. Strip the top byte before pread in PAL_ReadProcessMemory and createdump's ReadProcessMemory. This is a no-op on non-Android ARM64 Linux today, but guards against future TBI/MTE adoption on other distributions. See https://www.kernel.org/doc/html/latest/arch/arm64/tagged-address-abi.html

CopilotAI review requested due to automatic review settings February 21, 2026 19:49

github-actionsBot added the area-Diagnostics-coreclr label Feb 21, 2026

steveisok requested a review from a teamFebruary 21, 2026 19:49

dotnet-policy-serviceBot assigned steveisok Feb 21, 2026

Copilotstarted reviewing on behalf of steveisok February 21, 2026 19:49 View session

CopilotAI reviewed Feb 21, 2026
View reviewed changes

Comment threadsrc/coreclr/pal/src/debug/debug.cpp Outdated

TARGET_ARM64 guard in debug.cpp
aa385df

noahfalk approved these changes Feb 24, 2026
View reviewed changes

steveisok enabled auto-merge (squash) February 24, 2026 11:55

steveisok merged commit dad73ab into dotnet:mainFeb 24, 2026
99 of 105 checks passed

steveisok deleted the fix/arm64-strip-tbi-tags-pread branch February 24, 2026 11:56

dotnet-maestroBot mentioned this pull request Feb 25, 2026
[main] Source code updates from dotnet/runtime dotnet/dotnet#5050
Merged

github-actionsBot locked and limited conversation to collaborators Mar 27, 2026