gloo/tcp: fix size_t overflow in recv bounds check (relative write-what-where)#509
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…at-where) Summary: `tcp::Pair::prepareRead` validated incoming `SEND_BUFFER` payloads with `GLOO_ENFORCE_LE(op.preamble.roffset + op.preamble.length, op.buf->size_)`, where `roffset` and `length` are `size_t` fields read directly off the socket (`Op::preamble` in `pair.h`). The addition wraps modulo 2^64, so a malicious peer can pick e.g. `roffset = (size_t)-8` and `length = 8`: the sum wraps to `0`, passes the check, and `recv()` then writes attacker-controlled bytes at `((char*)op.buf->ptr_) + roffset` (= `ptr_ - 8`). Varying `(roffset, length)` pairs whose sum wraps to `<= size_` yields a relative write-what-where primitive at an arbitrary 64-bit offset from a registered buffer, with fully attacker-controlled content. Gloo `SECURITY.md` puts network-exploitable RCE in scope. This rewrites the check to validate each term independently so the sum cannot wrap: `roffset <= size_` and `length <= size_ - roffset`. This mirrors the existing overflow-safe pattern already used in `Pair::send`/`recv`/`tryRecv`. The check is also moved ahead of the `iov_base` computation so an out-of-bounds pointer is never formed — UBSan flagged the old `ptr_ + roffset` arithmetic itself as `pointer-overflow`, independent of the enforce. The same `prepareRead` is inherited by the TLS transport (`tcp::tls::Pair`), so both TCP and TCP+TLS are fixed by this change. Differential Revision: D108082771
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Regina8023
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Jun 10, 2026
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…87077) ## Summary Bumps the `gloo` submodule from `3135b0b` to `74cc005` (15 commits, 2026-01-09 -> 2026-06-10; +615/-144 across 29 files). The headline change is a **security fix**: a `size_t` overflow in the TCP transport's recv bounds check that allowed a relative write-what-where. `roffset` and `length` are read directly off the wire, and the old check `roffset + length <= size_` could wrap around 2^64, letting an out-of-bounds pair pass and yield an arbitrary write at `ptr_ + roffset`. The fix validates each term independently before forming the pointer. The rest is a mix of portability/bug fixes (ibverbs destructor crash on no-RDMA hosts, TCP address-family mismatch, ROCm `[[nodiscard]]` and `-Wnontrivial-memcall` warnings), toolchain/CI work (move to C++20, native CMake HIP support for ROCm, new CUDA/ROCm/arm64 CI runners, clang-format 21), and named gloo threads for observability. Note: the SHM allreduce optimization ([#458](pytorch/gloo#458)) was added then reverted ([#490](pytorch/gloo#490)) within this range, so it is **not** present in the final tree. ## Included commits (newest -> oldest) | Commit | Author | Date | Description | |--------|--------|------|-------------| | `74cc005` | Tristan Rice | 2026-06-10 | **gloo/tcp: fix size_t overflow in recv bounds check (relative write-what-where)** ([#509](pytorch/gloo#509)) | | `70dc360` | Tristan Rice | 2026-04-20 | Fix address family mismatch by reusing bound socket ([#503](pytorch/gloo#503)) | | `6f4c667` | Tristan Rice | 2026-03-19 | Fix `std::terminate` in ibverbs destructors on systems without RDMA hardware ([#500](pytorch/gloo#500)) | | `2ba34a6` | Karl Gyllstrom | 2026-03-11 | Fix `[[nodiscard]]` `cudaDeviceEnablePeerAccess` warning | | `845824e` | Richard Barnes | 2026-03-11 | Move gloo onto C++20 | | `bcd1672` | Gavin Zhao | 2026-02-12 | ROCm: Migrate to native CMake HIP support ([#478](pytorch/gloo#478)) | | `9322e67` | Tristan Rice | 2026-02-09 | Revert "Intra-node shared memory (SHM) optimizations" ([#490](pytorch/gloo#490)) | | `f834c75` | Tristan Rice | 2026-02-06 | gloo: improve error message on connection closed | | `8789be7` | Tristan Rice | 2026-02-05 | ci: add CUDA and rocm builds | | `d8d0f77` | Nathan Brown | 2026-02-05 | ci: add arm64 runner for github actions ([#487](pytorch/gloo#487)) | | `8d0b9a4` | Lydia Kim | 2026-01-14 | Fix `-Wnontrivial-memcall` | | `980c925` | Lucian Adrian Grijincu | 2026-01-13 | Fix `-Wnontrivial-memcall` error in AllreduceLocal | | `b9cac96` | Tristan Rice | 2026-01-13 | Add `setThreadName` helper and name all gloo threads | | `7ec708d` | Tristan Rice | 2026-01-12 | ci: bump linter to clang-format 21.1.2 | | `5994546` | gaopengff | 2026-01-09 | Intra-node shared memory (SHM) optimizations for CPU primitives ([#458](pytorch/gloo#458)) -- *later reverted by `9322e67`* | ## Test Plan CI. Submodule bump only; the gloo changes carry their own unit tests (TCP pair bounds-check coverage added in #509). Pull Request resolved: #187077 Approved by: https://github.com/dolpm, https://github.com/kapilsh, https://github.com/Regina8023, https://github.com/malfet
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Jun 13, 2026
…torch#187077) ## Summary Bumps the `gloo` submodule from `3135b0b` to `74cc005` (15 commits, 2026-01-09 -> 2026-06-10; +615/-144 across 29 files). The headline change is a **security fix**: a `size_t` overflow in the TCP transport's recv bounds check that allowed a relative write-what-where. `roffset` and `length` are read directly off the wire, and the old check `roffset + length <= size_` could wrap around 2^64, letting an out-of-bounds pair pass and yield an arbitrary write at `ptr_ + roffset`. The fix validates each term independently before forming the pointer. The rest is a mix of portability/bug fixes (ibverbs destructor crash on no-RDMA hosts, TCP address-family mismatch, ROCm `[[nodiscard]]` and `-Wnontrivial-memcall` warnings), toolchain/CI work (move to C++20, native CMake HIP support for ROCm, new CUDA/ROCm/arm64 CI runners, clang-format 21), and named gloo threads for observability. Note: the SHM allreduce optimization ([pytorch#458](pytorch/gloo#458)) was added then reverted ([pytorch#490](pytorch/gloo#490)) within this range, so it is **not** present in the final tree. ## Included commits (newest -> oldest) | Commit | Author | Date | Description | |--------|--------|------|-------------| | `74cc005` | Tristan Rice | 2026-06-10 | **gloo/tcp: fix size_t overflow in recv bounds check (relative write-what-where)** ([pytorch#509](pytorch/gloo#509)) | | `70dc360` | Tristan Rice | 2026-04-20 | Fix address family mismatch by reusing bound socket ([pytorch#503](pytorch/gloo#503)) | | `6f4c667` | Tristan Rice | 2026-03-19 | Fix `std::terminate` in ibverbs destructors on systems without RDMA hardware ([pytorch#500](pytorch/gloo#500)) | | `2ba34a6` | Karl Gyllstrom | 2026-03-11 | Fix `[[nodiscard]]` `cudaDeviceEnablePeerAccess` warning | | `845824e` | Richard Barnes | 2026-03-11 | Move gloo onto C++20 | | `bcd1672` | Gavin Zhao | 2026-02-12 | ROCm: Migrate to native CMake HIP support ([pytorch#478](pytorch/gloo#478)) | | `9322e67` | Tristan Rice | 2026-02-09 | Revert "Intra-node shared memory (SHM) optimizations" ([pytorch#490](pytorch/gloo#490)) | | `f834c75` | Tristan Rice | 2026-02-06 | gloo: improve error message on connection closed | | `8789be7` | Tristan Rice | 2026-02-05 | ci: add CUDA and rocm builds | | `d8d0f77` | Nathan Brown | 2026-02-05 | ci: add arm64 runner for github actions ([pytorch#487](pytorch/gloo#487)) | | `8d0b9a4` | Lydia Kim | 2026-01-14 | Fix `-Wnontrivial-memcall` | | `980c925` | Lucian Adrian Grijincu | 2026-01-13 | Fix `-Wnontrivial-memcall` error in AllreduceLocal | | `b9cac96` | Tristan Rice | 2026-01-13 | Add `setThreadName` helper and name all gloo threads | | `7ec708d` | Tristan Rice | 2026-01-12 | ci: bump linter to clang-format 21.1.2 | | `5994546` | gaopengff | 2026-01-09 | Intra-node shared memory (SHM) optimizations for CPU primitives ([pytorch#458](pytorch/gloo#458)) -- *later reverted by `9322e67`* | ## Test Plan CI. Submodule bump only; the gloo changes carry their own unit tests (TCP pair bounds-check coverage added in pytorch#509). Pull Request resolved: pytorch#187077 Approved by: https://github.com/dolpm, https://github.com/kapilsh, https://github.com/Regina8023, https://github.com/malfet
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Summary:
tcp::Pair::prepareReadvalidated incomingSEND_BUFFERpayloads withGLOO_ENFORCE_LE(op.preamble.roffset + op.preamble.length, op.buf->size_), whereroffsetandlengtharesize_tfields read directly off the socket (Op::preambleinpair.h). The addition wraps modulo 2^64, so a malicious peer can pick e.g.roffset = (size_t)-8andlength = 8: the sum wraps to0, passes the check, andrecv()then writes attacker-controlled bytes at((char*)op.buf->ptr_) + roffset(=ptr_ - 8). Varying(roffset, length)pairs whose sum wraps to<= size_yields a relative write-what-where primitive at an arbitrary 64-bit offset from a registered buffer, with fully attacker-controlled content. GlooSECURITY.mdputs network-exploitable RCE in scope.This rewrites the check to validate each term independently so the sum cannot wrap:
roffset <= size_andlength <= size_ - roffset. This mirrors the existing overflow-safe pattern already used inPair::send/recv/tryRecv. The check is also moved ahead of theiov_basecomputation so an out-of-bounds pointer is never formed — UBSan flagged the oldptr_ + roffsetarithmetic itself aspointer-overflow, independent of the enforce.The same
prepareReadis inherited by the TLS transport (tcp::tls::Pair), so both TCP and TCP+TLS are fixed by this change.Differential Revision: D108082771