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GET /api/1.2/patches/2230262/?format=api
{ "id": 2230262, "url": "http://patchwork.ozlabs.org/api/1.2/patches/2230262/?format=api", "web_url": "http://patchwork.ozlabs.org/project/glibc/patch/4024b75e5db1853b62dcd5147151a8f3433d46b8.1777472828.git.ashamil435@gmail.com/", "project": { "id": 41, "url": "http://patchwork.ozlabs.org/api/1.2/projects/41/?format=api", "name": "GNU C Library", "link_name": "glibc", "list_id": "libc-alpha.sourceware.org", "list_email": "libc-alpha@sourceware.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<4024b75e5db1853b62dcd5147151a8f3433d46b8.1777472828.git.ashamil435@gmail.com>", "list_archive_url": null, "date": "2026-04-29T14:29:18", "name": "[v2] libio: Fix race in _IO_new_file_init_internal initialization order [BZ #33785]", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "c0b9e3b57fc18015a12fa19d7f2c4daaf100dd24", "submitter": { "id": 93241, "url": "http://patchwork.ozlabs.org/api/1.2/people/93241/?format=api", "name": "Shamil Abdulaev", "email": "ashamil435@gmail.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/glibc/patch/4024b75e5db1853b62dcd5147151a8f3433d46b8.1777472828.git.ashamil435@gmail.com/mbox/", "series": [ { "id": 502080, "url": "http://patchwork.ozlabs.org/api/1.2/series/502080/?format=api", "web_url": "http://patchwork.ozlabs.org/project/glibc/list/?series=502080", "date": "2026-04-29T14:29:18", "name": "[v2] libio: Fix race in _IO_new_file_init_internal initialization order [BZ #33785]", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/502080/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2230262/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2230262/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "libc-alpha@sourceware.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "libc-alpha@sourceware.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=CdoinNEe;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org\n (client-ip=38.145.34.32; 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A concurrent thread that walks\n_IO_list_all (for example via fflush (NULL)) could observe the stream\nwith an uninitialized _fileno before initialization completed.\n\nSet _fileno = -1 before _IO_link_in so the stream is fully\ninitialized when it becomes visible in the global list.\n\nThis is the residual concurrency defect noted at the end of commit\nb657f72fa3 (\"libio: Fix deadlock between freopen, fflush (NULL) and\nfclose (bug 24963)\").\n\nAdd libio/tst-file-init-race exercising concurrent fopen/fclose and\nfflush (NULL) to detect regressions.\n\nSigned-off-by: Shamil Abdulaev <ashamil435@gmail.com>\n---\nChanges since v1:\n - Apply the same _fileno/_IO_link_in reordering to libio/oldfileops.c\n (suggested by Florian Weimer).\n - tst-file-init-race: treat fopen/fclose failures as test failures via\n FAIL_EXIT1 instead of silently ignoring them (suggested by Florian\n Weimer).\n\n libio/Makefile | 3 ++\n libio/fileops.c | 2 +-\n libio/oldfileops.c | 2 +-\n libio/tst-file-init-race.c | 69 ++++++++++++++++++++++++++++++++++++++\n 4 files changed, 74 insertions(+), 2 deletions(-)\n create mode 100644 libio/tst-file-init-race.c", "diff": "diff --git a/libio/Makefile b/libio/Makefile\nindex 93656466df..7e448295e3 100644\n--- a/libio/Makefile\n+++ b/libio/Makefile\n@@ -107,6 +107,7 @@ tests = \\\n tst-fgetc-after-eof \\\n tst-fgetwc \\\n tst-fgetws \\\n+ tst-file-init-race \\\n tst-fopenloc2 \\\n tst-fputws \\\n tst-freopen \\\n@@ -160,6 +161,8 @@ tests-static += \\\n \n $(objpfx)tst-popen-fork: $(shared-thread-library)\n \n+$(objpfx)tst-file-init-race: $(shared-thread-library)\n+\n tests-internal = tst-vtables tst-vtables-interposed\n \n ifeq (yes,$(build-shared))\ndiff --git a/libio/fileops.c b/libio/fileops.c\nindex 8067c0a9cf..9348d7c3a1 100644\n--- a/libio/fileops.c\n+++ b/libio/fileops.c\n@@ -111,8 +111,8 @@ _IO_new_file_init_internal (struct _IO_FILE_plus *fp)\n fp->file._offset = _IO_pos_BAD;\n fp->file._flags |= CLOSED_FILEBUF_FLAGS;\n \n- _IO_link_in (fp);\n fp->file._fileno = -1;\n+ _IO_link_in (fp);\n }\n \n /* External version of _IO_new_file_init_internal which switches off\ndiff --git a/libio/oldfileops.c b/libio/oldfileops.c\nindex 41b15491cb..0b92afbdb1 100644\n--- a/libio/oldfileops.c\n+++ b/libio/oldfileops.c\n@@ -108,8 +108,8 @@ _IO_old_file_init_internal (struct _IO_FILE_plus *fp)\n _IO_vtable_offset is used to detect the old binaries. */\n fp->file._vtable_offset = ((int) sizeof (struct _IO_FILE)\n \t\t\t - (int) sizeof (struct _IO_FILE_complete));\n- _IO_link_in (fp);\n fp->file._fileno = -1;\n+ _IO_link_in (fp);\n \n if (&_IO_stdin_used != NULL || !_IO_legacy_file ((FILE *) fp))\n /* The object is dynamically allocated and large enough. Initialize\ndiff --git a/libio/tst-file-init-race.c b/libio/tst-file-init-race.c\nnew file mode 100644\nindex 0000000000..7adaba272c\n--- /dev/null\n+++ b/libio/tst-file-init-race.c\n@@ -0,0 +1,69 @@\n+/* Test for race during FILE initialization in _IO_new_file_init_internal.\n+ Copyright (C) 2026 Free Software Foundation, Inc.\n+ This file is part of the GNU C Library.\n+\n+ The GNU C Library is free software; you can redistribute it and/or\n+ modify it under the terms of the GNU Lesser General Public\n+ License as published by the Free Software Foundation; either\n+ version 2.1 of the License, or (at your option) any later version.\n+\n+ The GNU C Library is distributed in the hope that it will be useful,\n+ but WITHOUT ANY WARRANTY; without even the implied warranty of\n+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU\n+ Lesser General Public License for more details.\n+\n+ You should have received a copy of the GNU Lesser General Public\n+ License along with the GNU C Library; if not, see\n+ <https://www.gnu.org/licenses/>. */\n+\n+#include <stdio.h>\n+#include <stdatomic.h>\n+#include <pthread.h>\n+#include <time.h>\n+\n+#include <support/check.h>\n+#include <support/xthread.h>\n+\n+static atomic_bool stop = ATOMIC_VAR_INIT (0);\n+\n+static void *\n+opener_thread (__attribute__ ((unused)) void *arg)\n+{\n+ while (!atomic_load_explicit (&stop, memory_order_acquire))\n+ {\n+ FILE *fp = fopen (\"/dev/null\", \"r\");\n+ if (fp == NULL)\n+ FAIL_EXIT1 (\"fopen: %m\");\n+ if (fclose (fp) != 0)\n+ FAIL_EXIT1 (\"fclose: %m\");\n+ }\n+ return NULL;\n+}\n+\n+static void *\n+flusher_thread (__attribute__ ((unused)) void *arg)\n+{\n+ while (!atomic_load_explicit (&stop, memory_order_acquire))\n+ fflush (NULL);\n+ return NULL;\n+}\n+\n+static int\n+do_test (void)\n+{\n+ pthread_t t1 = xpthread_create (NULL, opener_thread, NULL);\n+ pthread_t t2 = xpthread_create (NULL, flusher_thread, NULL);\n+\n+ struct timespec ts = { .tv_sec = 3, .tv_nsec = 0 };\n+ nanosleep (&ts, NULL);\n+\n+ atomic_store_explicit (&stop, 1, memory_order_release);\n+\n+ xpthread_join (t1);\n+ xpthread_join (t2);\n+\n+ return 0;\n+}\n+\n+#define TIMEOUT 30\n+#include <support/test-driver.c>\n", "prefixes": [ "v2" ] }