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{ "id": 2227576, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2227576/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/cover/20260424-master-v2-0-8b50b5c063ed@gmail.com/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/1.1/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260424-master-v2-0-8b50b5c063ed@gmail.com>", "date": "2026-04-23T21:36:37", "name": "[v2,0/3] linux-user: Filter /proc/*/task/ and validate tkill targets", "submitter": { "id": 93154, "url": "http://patchwork.ozlabs.org/api/1.1/people/93154/?format=api", "name": "Ali Raza", "email": "elirazamumtaz@gmail.com" }, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/cover/20260424-master-v2-0-8b50b5c063ed@gmail.com/mbox/", "series": [ { "id": 501265, "url": "http://patchwork.ozlabs.org/api/1.1/series/501265/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=501265", "date": "2026-04-23T21:36:37", "name": "linux-user: Filter /proc/*/task/ and validate tkill targets", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/501265/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2227576/comments/", "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=AIdOphpZ;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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charset=\"utf-8\"", "Content-Transfer-Encoding": "8bit", "X-B4-Tracking": "v=1; b=H4sIAOWQ6mkC/2WNwQ7CIBAFf6XZsxhAa4wn/8P0QGFp10gxgETT8\n O9CPXqcZN68FSIGwgiXboWAmSL5pYLcdaBntUzIyFQGyeWJH0XPnIoJAzsobpXE0UrTQ5WfAS2\n 9t9Bt+HF8jXfUqa2bMVNMPny2pyya9xfNgnF2NkaiFUIg4nVyih577R0MpZQv+dJ/Wq4AAAA=", "X-Change-ID": "20260415-master-3a0fa2ebf2d5", "To": "qemu-devel@nongnu.org", "Cc": "Ali Raza <elirazamumtaz@gmail.com>, Laurent Vivier <laurent@vivier.eu>,\n Pierrick Bouvier <pierrick.bouvier@linaro.org>,\n =?utf-8?q?Alex_Benn=C3=A9e?= <alex.bennee@linaro.org>, deller@gmx.de", "X-Mailer": "b4 0.15.2", "Received-SPF": "pass client-ip=2a00:1450:4864:20::42a;\n envelope-from=elirazamumtaz@gmail.com; helo=mail-wr1-x42a.google.com", "X-Spam_score_int": "-20", "X-Spam_score": "-2.1", "X-Spam_bar": "--", "X-Spam_report": "(-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no", "X-Spam_action": "no action", "X-Mailman-Approved-At": "Thu, 23 Apr 2026 20:42:33 -0400", "X-BeenThere": "qemu-devel@nongnu.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "This series fixes a problem where QEMU user-mode exposes internal\nhost threads (RCU, TCG workers) to guest processes via /proc/*/task/\nand allows the guest to signal them via tkill/tgkill.\n\nPatch 1: Filters getdents/getdents64 on /proc/<pid>/task/\nPatch 2: Validates tkill/tgkill targets against guest CPU list\nPatch 3: Adds a multiarch test exercising both fixes\n\nSigned-off-by: Ali Raza <elirazamumtaz@gmail.com>\n---\nChanges in v2:\n- linux-user/syscall.c: use pid_t instead of long for the tid variable\n in do_getdents() and do_getdents64() (suggested by Helge Deller).\n- linux-user/syscall.c: replace ad-hoc readlink-at-getdents check with\n fd_trans-based tagging at open time, eliminating a TOCTOU race and\n a broad-prefix match that also matched /proc/<pid>/task/<tid>/fd.\n- linux-user/syscall.c (do_getdents, do_getdents64): retry sys_getdents\n when an entire host batch is filtered out, so the guest does not see\n a false EOF.\n- linux-user/syscall.c (do_getdents, do_getdents64): parse the dirent\n TID with qemu_strtoi() instead of strtol() so out-of-range values\n cannot wrap silently into pid_t.\n- linux-user/syscall.c (do_tkill): validate the guest tid range against\n pid_t and only reject signals whose target lives in our own host\n process and is not a guest thread (allow cross-process tkill to fall\n through to the kernel).\n- linux-user/syscall.c (do_tgkill): drop the previous tgid==getpid()\n blanket rejection and apply the same in-our-process-only filter, so\n legitimate cross-process tgkill keeps working.\n- tests/tcg/multiarch/linux-proc-task.c: hard-assert ESRCH on tkill to\n a non-guest tid, and add tgkill coverage (success on guest tids,\n ESRCH on a wrong tgid).\n- Link to v1: https://lore.kernel.org/qemu-devel/20260415-master-v1-0-8dd2ef111eee@gmail.com\n\nTo: qemu-devel@nongnu.org\nCc: Laurent Vivier <laurent@vivier.eu>\nCc: Pierrick Bouvier <pierrick.bouvier@linaro.org>\nCc: Alex Bennée <alex.bennee@linaro.org>\n\n---\nAli Raza (3):\n linux-user: Filter /proc/*/task/ to hide QEMU-internal threads\n linux-user: Validate tkill/tgkill targets are guest threads\n tests/tcg: Add test for /proc/self/task/ filtering and tkill validation\n\n linux-user/fd-trans.c | 6 +\n linux-user/fd-trans.h | 18 ++\n linux-user/syscall.c | 353 +++++++++++++++++++++-------\n tests/tcg/multiarch/Makefile.target | 2 +\n tests/tcg/multiarch/linux/linux-proc-task.c | 193 +++++++++++++++\n 5 files changed, 492 insertions(+), 80 deletions(-)\n---\nbase-commit: da6c4fe60fee30dd77267764d55b38af9cb89d4b\nchange-id: 20260415-master-3a0fa2ebf2d5\n\nBest regards,\n-- \nAli Raza <elirazamumtaz@gmail.com>" }