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b=UB7f7OhWq1DxpKTgfVroj21MHn7Asx3BUizcAKwgMLDZI89Ej0SK4pvtDO+QrYvBq LUpuQp7ZGpyjzVXCp2OVa4TTmYXwP6+QGEBMkRdWcUT3UUviOFeQ++kU8MwDuj+MpU xk4iMSPnBlscuNkNry6+AtEEAL/JBFT2ENYY7sk5LnTXPOSdCKMwBGZT4iqhscLdbw qMcnDIXZpulbTFQIbJ9XMIp5nDa3BEvWTFh/NOoyR5Mf13Amwb0ymTEm/XQYAQeItP 3DeakQqDplWN6tcYhTP36A3jhIKTIcU2rhwSrs2lSPslf0aIiSHgh0Fec8e1aXhmDe 4s9bQvFqRFFwA== From: Christian Brauner Subject: [PATCH 0/3] binfmt_misc: only let punctuation delimit a register string Date: Wed, 26 Aug 2026 17:55:45 +0200 Message-Id: <20260826-work-binfmt_misc-delim-v1-0-43618adf8599@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/03M0QrCMAyF4VcZuTal62AMX0VE2i51UddJs6kw9 u6288bLP5x8KwglJoFjtUKiFwtPMUd9qMAPNl4Juc8NRptWd7XG95Tu6DiGcb6MLB57evCIXRN a450PZBrIz89EgT87fDr/WhZ3Iz8XrSycFUKXbPRDORVX/blqd1VZwbZ9AfjKkpGoAAAA X-Change-ID: 20260810-work-binfmt_misc-delim-83f62cbcfe23 To: linux-fsdevel@vger.kernel.org Cc: Alexander Viro , Jan Kara , Kees Cook , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-doc@vger.kernel.org, Farid Zakaria , "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-362b8 X-Developer-Signature: v=1; a=openpgp-sha256; l=1243; i=brauner@kernel.org; h=from:subject:message-id; bh=Phb72AoqbVHIC31C23WEo20gDWkMp0/dpMPIljHQDwM=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWT183Qz3+6pPNDT/i0r7sXcF57JC4O2usbrec2s+HdOz 8dlQt3CjlIWBjEuBlkxRRaHdpNwueU8FZuNMjVg5rAygQxh4OIUgIlYX2dkeOHV7qt0W9bnfazv rh2nMjKV76gViE2MzLH3cK+6+Uarn5Fh8caLLOWfL3MtXaPKqF/f/TL7zOnJO8WnL8v9wHniVuw EDgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Stat-Signature: n16xaduegoes87q3uowk7po7mraik9wo X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: AF5E64000F X-Rspam-User: X-HE-Tag: 1787759759-818983 X-HE-Meta: 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 2jqEarJN eD8bAlMJVpbMR7EYwaM3vrLeg8nBGhAsMcD6GtxwstMC18rGurmk/5Ceis2DK+UztXXI+3kTt0cO1TfK9g3FHM6Meic29MozyF1ygGAZZkfd1wbViURJ8a1pkmktP4DkyQebalEvtgw0SXPBETvragnGPsJoNnM5y424eAbhzEs7zuO8y9/K4M0vEuQQCtAzekYUQ3Oghhdg5rdyyKFa4iWkeyqWFiCN5AqfBdlODSoDokbs367SWnHLz/maUBIlJLDhpWiIpZ7b/f81WF/dYgqOBzI8SjhQiIaMZs+G2883CJBnIHap66la2I4qdmfiSEAxHsp5yhmSmnQHn+cQVaEPPXdp2AlA11NT8/GaPwLJZCMU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently we accept arbitrary delimiters which really makes no sense and from looking around it's an unused feature. Everytime we add a flag the number of possible delimiter shrinks and it makes extensions much more hazardous than they need to be. Stop it and only accept punctional as delimiters. This extends commit 8e85d50ba111 ("binfmt_misc: reject a flag character as the field delimiter"). Letters, digits, whitespace, control characters, bytes above 0x7f and the backslash now get -EINVAL. Everything deployed uses ':' anyway. Signed-off-by: Christian Brauner (Amutable) --- Christian Brauner (3): binfmt_misc: only let punctuation delimit a register string selftests/exec: test delimiter restrictions binfmt_misc: document the field delimiter Documentation/admin-guide/binfmt-misc.rst | 3 + fs/binfmt_misc.c | 12 ++- tools/testing/selftests/exec/Makefile | 4 + tools/testing/selftests/exec/binfmt_misc_delim.c | 127 +++++++++++++++++++++++ 4 files changed, 143 insertions(+), 3 deletions(-) --- base-commit: 66498c75b4f8017f62d720d9b59675bdf3abce91 change-id: 20260810-work-binfmt_misc-delim-83f62cbcfe23