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xcb connect_to_fd* constructors unsound #2355

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Merged
merged 2 commits into from
Aug 22, 2025
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xcb connect_to_fd* constructors unsound #2355

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accdd69
Report xcb connect_to_fd soundness issue
En-En-Code Aug 5, 2025
a963a11
modify notice to include fix information
En-En-Code Aug 21, 2025
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32 changes: 32 additions & 0 deletions crates/xcb/RUSTSEC-0000-0000.md
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```toml
[advisory]
id = "RUSTSEC-0000-0000"
package = "xcb"
date = "2025-08-05"
url = "https://github.com/rust-x-bindings/rust-xcb/issues/282"
references = [
"https://github.com/rust-x-bindings/rust-xcb/issues/167",
"https://github.com/rust-x-bindings/rust-xcb/pull/283"
]
informational = "unsound"

[versions]
patched = [">= 1.6.0"]

[affected.functions]
"xcb::Connection::connect_to_fd" = [">= 1.0.0-beta.0"]
"xcb::Connection::connect_to_fd_with_extensions" = [">= 1.0.0-beta.0"]
```

# `xcb::Connection::connect_to_fd*` functions violate I/O safety

The API of `xcb::Connection` has constructors which allow an arbitrary `RawFd`
to be used as a socket connection. On either failure of these constructors or
on the drop of `Connection`, it closes the associated file descriptor. Thus, a
program which uses an `OwnedFd` (such as a `UnixStream`) as the file descriptor
can close the file descriptor and continue to attempt using it or close an
already-closed file descriptor, violating I/O safety.

Starting in version 1.6.0, `xcb` provides `Connection::connect_with_fd` and
`Connection::connect_with_fd_and_extensions` as safe alternatives and
deprecates the problematic functions.