From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794435132; b=etKKPJo2YROFe4QDaxDbcAnKhCAGqIIa/rigW28VsnBdw2486zLs0u3b1XGMpXlatvIC mRqvVzN4zUa9AFNgPu1jpWUVF00dJenu8kYYG6eink6sYL3AIJt+sMBFX3xjCpeBqKWNf kHNW2JCFoSDm6WfhbvJUz8d1gD8BM/yx7Oe0MKelhKPh05Pup4Qm9hjJXysGUog9fms/V F+72AHlMNUyOE9/jI2Otifhr8TQFrGm4Q7RwBhAOLN2HYrp0cRZNT2L9wFj7gl6KyivOk y4jWEfsRbrCHtTTgnVAJSP9zHxCJmi8UknM+283xmTkY3I2vGjbwLfB40WqqIBj6yAQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794435132; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=4cRXkekRFtgzW6q7qZoQEfRml3hkrUaefLqv1KtKVRI=; b=V+7W+uh/WLc+BJ1iGsQxeQCoqRea38GE54+JHOUy4jDEBP8ALSvzT+fZYgEnWa2nfmaO Y53sTwDNVGM7hvA1tIcrw4TcEUm9jCSncYdL/95CSa/uVu/HmNHaQWTR+8pBeoM4uRk9y r3sD6SzGxykQOMb7i/A9XIBze1J/jBP/IR5qwrWadC+bTiHGEIDOTteTlvRLE9XA/DUKE AL87sF1HjycTk5FN08+7Vx4s66sE5zPBLcDc4v9BK9+wRSu5qUBfDha+AldkvsVh7XKkR +YgHG/HFlbvx31Rwz71I99LBaNkEKgTwZbOdQ1ymLKmebs1dbCFcE/zEhpyp2jINfFQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=LpTWFr4X; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F3235606A31C for ; Wed, 11 Nov 2026 22:12:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=LpTWFr4X Received: by smtp.kernel.org (Postfix) with ESMTPSA id 186911F00A05; Wed, 11 Nov 2026 22:12:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794435131; bh=4cRXkekRFtgzW6q7qZoQEfRml3hkrUaefLqv1KtKVRI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LpTWFr4XcHmGK6za8RRMfFec+cmKUtzmXjCJ/0I0QXdTfEXsULZcIn9Z1CVCbJkIW QixnWi1hVGOWngTKz7/ImerQ+oLSWwfqMEcKSFGhW7cHSWXgEAn/wtJ/EPLj9k7Xvc 3PX361ahPGZTUTjN7eN8U0HeLb0Ef7YZrOr2xSSrPjFeqFOWjY7Os0wH7pjsU1J6tn QOQlJtareCtU5+XcRVR63V9SnAGmqEsbQQF+Z+dXh6zOP+WXLmgdgX8ynTuEneST6p 4ghVgc2majMC/+VZJxhcSMZT0I4xYi01Vb0X1GONUPeKfgkccUZAxqKAjvlfz5J6n7 lX0Ln9VT4fuNQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Al Viro , Shuah Khan , Sasha Levin Subject: [PATCH 5.15.y 1/2] selftests:core: test coverage for dup_fd() failure handling in unshare_fd() Date: Wed, 11 Nov 2026 17:12:08 -0500 Message-ID: <20261111221154.4123375-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107060233-failed-5.15-df0b7e0ea59c@kernel.org> References: <20261107060233-failed-5.15-df0b7e0ea59c@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Al Viro [ Upstream commit 611fbeb44a777e5ab54ab3127ec85f72147911d8 ] At some point there'd been a dumb braino during the dup_fd() calling conventions change; caught by smatch and immediately fixed. The trouble is, there had been no test coverage for the dup_fd() failure handling - neither in kselftests nor in LTP. Fortunately, it can be triggered on stock kernel - ENOMEM would require fault injection, but EMFILE can be had with sysctl alone (fs.nr_open). Add a test for dup_fd() failure. Fixed up commit log and short log - Shuah Khan Signed-off-by: Al Viro Signed-off-by: Shuah Khan Stable-dep-of: df0b7e0ea59c ("selftests/core: fix unshare_test with large fs.nr_open") Signed-off-by: Sasha Levin --- tools/testing/selftests/core/Makefile | 2 +- tools/testing/selftests/core/unshare_test.c | 94 +++++++++++++++++++++ 2 files changed, 95 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/core/unshare_test.c diff --git a/tools/testing/selftests/core/Makefile b/tools/testing/selftests/core/Makefile index f6f2d6f473c6a..8cc2b79dfa4c8 100644 --- a/tools/testing/selftests/core/Makefile +++ b/tools/testing/selftests/core/Makefile @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only CFLAGS += -g -I../../../../usr/include/ -TEST_GEN_PROGS := close_range_test +TEST_GEN_PROGS := close_range_test unshare_test include ../lib.mk diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c new file mode 100644 index 0000000000000..7fec9dfb1b0e3 --- /dev/null +++ b/tools/testing/selftests/core/unshare_test.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../kselftest_harness.h" +#include "../clone3/clone3_selftests.h" + +TEST(unshare_EMFILE) +{ + pid_t pid; + int status; + struct __clone_args args = { + .flags = CLONE_FILES, + .exit_signal = SIGCHLD, + }; + int fd; + ssize_t n, n2; + static char buf[512], buf2[512]; + struct rlimit rlimit; + int nr_open; + + fd = open("/proc/sys/fs/nr_open", O_RDWR); + ASSERT_GE(fd, 0); + + n = read(fd, buf, sizeof(buf)); + ASSERT_GT(n, 0); + ASSERT_EQ(buf[n - 1], '\n'); + + ASSERT_EQ(sscanf(buf, "%d", &nr_open), 1); + + ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit)); + + /* bump fs.nr_open */ + n2 = sprintf(buf2, "%d\n", nr_open + 1024); + lseek(fd, 0, SEEK_SET); + write(fd, buf2, n2); + + /* bump ulimit -n */ + rlimit.rlim_cur = nr_open + 1024; + rlimit.rlim_max = nr_open + 1024; + EXPECT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit)) { + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + exit(EXIT_FAILURE); + } + + /* get a descriptor past the old fs.nr_open */ + EXPECT_GE(dup2(2, nr_open + 64), 0) { + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + exit(EXIT_FAILURE); + } + + /* get descriptor table shared */ + pid = sys_clone3(&args, sizeof(args)); + EXPECT_GE(pid, 0) { + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + exit(EXIT_FAILURE); + } + + if (pid == 0) { + int err; + + /* restore fs.nr_open */ + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + /* ... and now unshare(CLONE_FILES) must fail with EMFILE */ + err = unshare(CLONE_FILES); + EXPECT_EQ(err, -1) + exit(EXIT_FAILURE); + EXPECT_EQ(errno, EMFILE) + exit(EXIT_FAILURE); + exit(EXIT_SUCCESS); + } + + EXPECT_EQ(waitpid(pid, &status, 0), pid); + EXPECT_EQ(true, WIFEXITED(status)); + EXPECT_EQ(0, WEXITSTATUS(status)); +} + +TEST_HARNESS_MAIN -- 2.53.0