-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-23:15.libc Security Advisory The FreeBSD Project Topic: libc stdio buffer overflow Category: core Module: libc Announced: 2023-11-07 Credits: inooo All supported versions of FreeBSD. Corrected: 2023-11-07 17:31:34 UTC (stable/14, 14.0-STABLE) 2023-11-08 00:45:25 UTC (releng/14.0, 14.0-RC4-p1) 2023-11-07 18:41:55 UTC (stable/13, 13.2-STABLE) 2023-11-08 00:48:03 UTC (releng/13.2, 13.2-RELEASE-p5) 2023-11-08 14:30:51 UTC (stable/12, 12.4-STABLE) 2023-11-08 01:09:31 UTC (releng/12.4, 12.4-RELEASE-p7) CVE Name: CVE-2023-5941 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . 0. Revision History v1.0 2023-11-07 -- Initial release v1.1 2023-11-29 -- Corrected stable/14 and stable/13 Correction details I. Background The FreeBSD C library (libc) Standard I/O (stdio) component provides essential functionality for input and output operations including file handling and buffering. It includes functions like "fopen", "printf", and "fflush". Streams may be unbuffered, line buffered, or fully buffered. The library writes buffered data when the buffer is full or when the application explicitly requests so by calling the fflush(3) function. II. Problem Description For line-buffered streams the __sflush() function did not correctly update the FILE object's write space member when the write(2) system call returns an error. III. Impact Depending on the nature of an application that calls libc's stdio functions and the presence of errors returned from the write(2) system call (or an overridden stdio write routine) a heap buffer overflow may occur. Such overflows may lead to data corruption or the execution of arbitrary code at the privilege level of the calling program. IV. Workaround No workaround is available. V. Solution Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. Perform one of the following: 1) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the amd64, i386, or (on FreeBSD 13 and later) arm64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install # shutdown -r +10min "Rebooting for a security update" 2) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 14.0] # fetch https://security.FreeBSD.org/patches/SA-23:15/stdio.14.patch # fetch https://security.FreeBSD.org/patches/SA-23:15/stdio.14.patch.asc # gpg --verify stdio.14.patch.asc [FreeBSD 13.2] # fetch https://security.FreeBSD.org/patches/SA-23:15/stdio.13.patch # fetch https://security.FreeBSD.org/patches/SA-23:15/stdio.13.patch.asc # gpg --verify stdio.13.patch.asc [FreeBSD 12.4] # fetch https://security.FreeBSD.org/patches/SA-23:15/stdio.12.patch # fetch https://security.FreeBSD.org/patches/SA-23:15/stdio.12.patch.asc # gpg --verify stdio.12.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile the operating system using buildworld and installworld as described in . Restart all daemons that use the library, or reboot the system. VI. Correction details This issue is corrected by the corresponding Git commit hash or Subversion revision number in the following stable and release branches: Branch/path Hash Revision - ------------------------------------------------------------------------- stable/14/ d2c65a1c9486 stable/14-n265707 releng/14.0/ 1f9c4610dde5 releng/14.0-n265376 stable/13/ 0b7939d725ba stable/13-n256681 releng/13.2/ d51a39b13ee4 releng/13.2-n254639 stable/12/ r373263 releng/12.4/ r373265 - ------------------------------------------------------------------------- For FreeBSD 13 and later: Run the following command to see which files were modified by a particular commit: # git show --stat Or visit the following URL, replacing NNNNNN with the hash: To determine the commit count in a working tree (for comparison against nNNNNNN in the table above), run: # git rev-list --count --first-parent HEAD For FreeBSD 12 and earlier: Run the following command to see which files were modified by a particular revision, replacing NNNNNN with the revision number: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEthUnfoEIffdcgYM7bljekB8AGu8FAmVnmQkACgkQbljekB8A Gu/QUA/+L3iTtXqyMYWT/uI8JHbc+cFjS89GOd14jV2MKUT9ajkUcmkEDC2atzXT rUswGxo1sPWZtuVaKdDQrhT12bTKJzV2C0NK0Doj+f9EDEmphvf9kpleMAwkeloR g5idsHgEN+gmQHR4Ki5oofvk6FlvGacan407rTvmRdEdTobO4ZM2zOTeTgcCMwzA dyA+CeRSIRluVdzu56PLVLYimgs0Xni/JmEatFXXXjGb25lIb4YDq32uO9Xvdhhi 7cRX6MiFsh702Tt6mo7ajo5B85khOEH/vlJkvgBQ8dcfaGIwpM00SoZFbL1SHk4y XSM92YK42XY8ME0gJDndM7gcEy9aODFJTtUuga57Og676/LRlJBVS8xh3kReT6p1 QY1fmnYXzCmIalumvcY1DjFWBPLDddLLuGIQoBtTHFPd3DDEg7ZpLSUUUqZGmQ+3 oJSLxBz5Ig+D50MlgD/R8Zmzn4bMCCjZjYahJtK/cjZzC0u5jlDfiF6lofETAypH oU9LM9M1lEOxuPS8a+1oCtJn3HZaYNgPp+8NajJlDeDzXpOo8+9cpm+9M5yjxIOF mARYZDD42diF3S8Z4ax6Z3H13CxcwHjTZSqVFf3JYpuZehz5aFgZ0xK7AVBWm5We 4JZ+vwZqdmvSDL00aEdaVJQ4bGxKREwq2cF2grtXWf5nS4ApB0s= =koz0 -----END PGP SIGNATURE-----