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The API says that CMSG_SPACE should be used for msg_controllen, but in practice the native ABI allows you to only use CMSG_LEN for the final (typically only) control message, and real-world software does this, including Wayland. For freebsd32, this is in practice mostly harmless, since control messages are generally used to carry file descriptors, which are already 4 bytes in size and thus no padding is needed, but they can carry other quantities that may not result in an aligned length. This was discovered after CheriBSD's freebsd64 equivalent was updated to match the freebsd32 implementation, as that uses 8 byte alignment which does break the file descriptor use case, and thus Wayland. This used to be addressed by aligning buflen before the first iteration, but that allowed unwanted invalid inputs and was lost in1b1428dcc8, with no safer equivalent put in its place. Reviewed by: brooks, kib, markj Obtained from: CheriBSD Fixes:1b1428dcc8("Fix a TOCTOU vulnerability in freebsd32_copyin_control().") Differential Revision: https://reviews.freebsd.org/D36554 (cherry picked from commit7b673a2c73)
FreeBSD Kernel Source:
This directory contains the source files and build glue that make up the FreeBSD kernel and its modules, including both original and contributed software.
Kernel configuration files are located in the conf/ subdirectory of each
architecture. GENERIC is the configuration used in release builds. NOTES
contains documentation of all possible entries. LINT is a compile-only
configuration used to maximize build coverage and detect regressions.
Source Roadmap:
| Directory | Description |
|---|---|
| amd64 | AMD64 (64-bit x86) architecture support |
| arm | 32-bit ARM architecture support |
| arm64 | 64-bit ARM (AArch64) architecture support |
| cam | Common Access Method storage subsystem - cam(4) and ctl(4) |
| cddl | CDDL-licensed optional sources such as DTrace |
| conf | kernel build glue |
| compat | Linux compatibility layer, FreeBSD 32-bit compatibility |
| contrib | 3rd-party imported software such as OpenZFS |
| crypto | crypto drivers |
| ddb | interactive kernel debugger - ddb(4) |
| fs | most filesystems, excluding UFS, NFS, and ZFS |
| dev | device drivers |
| gdb | kernel remote GDB stub - gdb(4) |
| geom | GEOM framework - geom(4) |
| i386 | i386 (32-bit x86) architecture support |
| kern | main part of the kernel |
| libkern | libc-like and other support functions for kernel use |
| modules | kernel module infrastructure |
| net | core networking code |
| net80211 | wireless networking (IEEE 802.11) - net80211(4) |
| netgraph | graph-based networking subsystem - netgraph(4) |
| netinet | IPv4 protocol implementation - inet(4) |
| netinet6 | IPv6 protocol implementation - inet6(4) |
| netipsec | IPsec protocol implementation - ipsec(4) |
| netpfil | packet filters - ipfw(4), pf(4), and ipfilter(4) |
| opencrypto | OpenCrypto framework - crypto(7) |
| powerpc | PowerPC/POWER (32 and 64-bit) architecture support |
| riscv | 64-bit RISC-V architecture support |
| security | security facilities - audit(4) and mac(4) |
| sys | kernel headers |
| tests | kernel unit tests |
| ufs | Unix File System - ffs(7) |
| vm | virtual memory system |
| x86 | code shared by AMD64 and i386 architectures |