kernel/linux.git/tools/testing/selftests/memfd, branch v6.6.131

selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT

2026-03-04T12:20:16+00:00

[ Upstream commit b24335521de92fd2ee22460072b75367ca8860b0 ] selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT In order to synchronize new processes to test inheritance of memfd_noexec sysctl, memfd_test sets up the sysctl with a value before creating the new process. The new process then sends itself a SIGSTOP in order to wait for the parent to flip the sysctl value and send a SIGCONT signal. This would work as intended if it wasn't the fact that the new process is being created with CLONE_NEWPID, which creates a new PID namespace and the new process has PID 1 in this namespace. There're restrictions on sending signals to PID 1 and, although it's relaxed for other than root PID namespace, it's biting us here. In this specific case the SIGSTOP sent by the new process is ignored (no error to kill() is returned) and it never stops its execution. This is usually not noticiable as the parent usually manages to set the new sysctl value before the child has a chance to run and the test succeeds. But if you run the test in a loop, it eventually reproduces: while [ 1 ]; do ./memfd_test >log 2>&1 || break; done; cat log So this patch replaces the SIGSTOP/SIGCONT synchronization with IPC semaphore. Link: https://lkml.kernel.org/r/a7776389-b3d6-4b18-b438-0b0e3ed1fd3b@work Fixes: 6469b66e3f5a ("selftests: improve vm.memfd_noexec sysctl tests") Signed-off-by: Aristeu Rozanski Cc: Aleksa Sarai Cc: Shuah Khan Cc: liuye Cc: Lorenzo Stoakes Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

selftests/memfd: delete unused declarations

2026-03-04T12:20:16+00:00

[ Upstream commit a9117b4d7f178ea36e8d256f8ab3752839e245b2 ] Commit 32d118ad50a5 ("selftests/memfd: add tests for F_SEAL_EXEC"): - added several unused 'nbytes' local variables Commit 6469b66e3f5a ("selftests: improve vm.memfd_noexec sysctl tests"): - orphaned 'newpid_thread_fn2()' forward declaration - orphaned 'join_newpid_thread()' forward declaration - added unused 'pid' local in sysctl_simple_child() - orphaned 'fd' local in sysctl_simple_child() - added unused 'fd' in sysctl_nested_child() Delete the unused locals and forward declarations. Link: https://lkml.kernel.org/r/20240118095057.677544-1-gthelen@google.com Signed-off-by: Greg Thelen Cc: Aleksa Sarai Cc: Daniel Verkamp Cc: Jeff Xu Cc: Kees Cook Cc: Shuah Khan Signed-off-by: Andrew Morton Stable-dep-of: b24335521de9 ("selftests/memfd: use IPC semaphore instead of SIGSTOP/SIGCONT") Signed-off-by: Sasha Levin

selftests/memfd: add test for mapping write-sealed memfd read-only

2025-08-28T14:28:39+00:00

From: Lorenzo Stoakes [ Upstream commit ea0916e01d0b0f2cce1369ac1494239a79827270 ] Now we have reinstated the ability to map F_SEAL_WRITE mappings read-only, assert that we are able to do this in a test to ensure that we do not regress this again. Link: https://lkml.kernel.org/r/a6377ec470b14c0539b4600cf8fa24bf2e4858ae.1732804776.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Cc: Jann Horn Cc: Julian Orth Cc: Liam R. Howlett Cc: Linus Torvalds Cc: Shuah Khan Cc: Vlastimil Babka Signed-off-by: Andrew Morton Cc: stable@vger.kernel.org Signed-off-by: Isaac J. Manjarres Signed-off-by: Greg Kroah-Hartman

selftests/memfd: run sysctl tests when PID namespace support is enabled

2024-12-27T12:58:55+00:00

commit 6a75f19af16ff482cfd6085c77123aa0f464f8dd upstream. The sysctl tests for vm.memfd_noexec rely on the kernel to support PID namespaces (i.e. the kernel is built with CONFIG_PID_NS=y). If the kernel the test runs on does not support PID namespaces, the first sysctl test will fail when attempting to spawn a new thread in a new PID namespace, abort the test, preventing the remaining tests from being run. This is not desirable, as not all kernels need PID namespaces, but can still use the other features provided by memfd. Therefore, only run the sysctl tests if the kernel supports PID namespaces. Otherwise, skip those tests and emit an informative message to let the user know why the sysctl tests are not being run. Link: https://lkml.kernel.org/r/20241205192943.3228757-1-isaacmanjarres@google.com Fixes: 11f75a01448f ("selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC") Signed-off-by: Isaac J. Manjarres Reviewed-by: Jeff Xu Cc: Suren Baghdasaryan Cc: Kalesh Singh Cc: [6.6+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

selftests: improve vm.memfd_noexec sysctl tests

2023-08-21T20:38:00+00:00

This adds proper tests for the nesting functionality of vm.memfd_noexec as well as some minor cleanups to spawn_*_thread(). Link: https://lkml.kernel.org/r/20230814-memfd-vm-noexec-uapi-fixes-v2-5-7ff9e3e10ba6@cyphar.com Signed-off-by: Aleksa Sarai Cc: Christian Brauner Cc: Daniel Verkamp Cc: Dominique Martinet Cc: Jeff Xu Cc: Kees Cook Cc: Shuah Khan Signed-off-by: Andrew Morton

memfd: do not -EACCES old memfd_create() users with vm.memfd_noexec=2

2023-08-21T20:37:59+00:00

Given the difficulty of auditing all of userspace to figure out whether every memfd_create() user has switched to passing MFD_EXEC and MFD_NOEXEC_SEAL flags, it seems far less distruptive to make it possible for older programs that don't make use of executable memfds to run under vm.memfd_noexec=2. Otherwise, a small dependency change can result in spurious errors. For programs that don't use executable memfds, passing MFD_NOEXEC_SEAL is functionally a no-op and thus having the same In addition, every failure under vm.memfd_noexec=2 needs to print to the kernel log so that userspace can figure out where the error came from. The concerns about pr_warn_ratelimited() spam that caused the switch to pr_warn_once()[1,2] do not apply to the vm.memfd_noexec=2 case. This is a user-visible API change, but as it allows programs to do something that would be blocked before, and the sysctl itself was broken and recently released, it seems unlikely this will cause any issues. [1]: https://lore.kernel.org/Y5yS8wCnuYGLHMj4@x1n/ [2]: https://lore.kernel.org/202212161233.85C9783FB@keescook/ Link: https://lkml.kernel.org/r/20230814-memfd-vm-noexec-uapi-fixes-v2-2-7ff9e3e10ba6@cyphar.com Fixes: 105ff5339f49 ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC") Signed-off-by: Aleksa Sarai Cc: Dominique Martinet Cc: Christian Brauner Cc: Daniel Verkamp Cc: Jeff Xu Cc: Kees Cook Cc: Shuah Khan Cc: Signed-off-by: Andrew Morton

selftests: memfd: error out test process when child test fails

2023-08-21T20:37:59+00:00

Patch series "memfd: cleanups for vm.memfd_noexec", v2. The most critical issue with vm.memfd_noexec=2 (the fact that passing MFD_EXEC would bypass it entirely[1]) has been fixed in Andrew's tree[2], but there are still some outstanding issues that need to be addressed: * vm.memfd_noexec=2 shouldn't reject old-style memfd_create(2) syscalls because it will make it far to difficult to ever migrate. Instead it should imply MFD_EXEC. * The dmesg warnings are pr_warn_once(), which on most systems means that they will be used up by systemd or some other boot process and userspace developers will never see it. - For the !(flags & (MFD_EXEC | MFD_NOEXEC_SEAL)) case, outputting a rate-limited message to the kernel log is necessary to tell userspace that they should add the new flags. Arguably the most ideal way to deal with the spam concern[3,4] while still prompting userspace to switch to the new flags would be to only log the warning once per task or something similar. However, adding something to task_struct for tracking this would be needless bloat for a single pr_warn_ratelimited(). So just switch to pr_info_ratelimited() to avoid spamming the log with something that isn't a real warning. There's lots of info-level stuff in dmesg, it seems really unlikely that this should be an actual problem. Most programs are already switching to the new flags anyway. - For the vm.memfd_noexec=2 case, we need to log a warning for every failure because otherwise userspace will have no idea why their previously working program started returning -EACCES (previously -EINVAL) from memfd_create(2). pr_warn_once() is simply wrong here. * The racheting mechanism for vm.memfd_noexec makes it incredibly unappealing for most users to enable the sysctl because enabling it on &init_pid_ns means you need a system reboot to unset it. Given the actual security threat being protected against, CAP_SYS_ADMIN users being restricted in this way makes little sense. The argument for this ratcheting by the original author was that it allows you to have a hierarchical setting that cannot be unset by child pidnses, but this is not accurate -- changing the parent pidns's vm.memfd_noexec setting to be more restrictive didn't affect children. Instead, switch the vm.memfd_noexec sysctl to be properly hierarchical and allow CAP_SYS_ADMIN users (in the pidns's owning userns) to lower the setting as long as it is not lower than the parent's effective setting. This change also makes it so that changing a parent pidns's vm.memfd_noexec will affect all descendants, providing a properly hierarchical setting. The performance impact of this is incredibly minimal since the maximum depth of pidns is 32 and it is only checked during memfd_create(2) and unshare(CLONE_NEWPID). * The memfd selftests would not exit with a non-zero error code when certain tests that ran in a forked process (specifically the ones related to MFD_EXEC and MFD_NOEXEC_SEAL) failed. [1]: https://lore.kernel.org/all/ZJwcsU0vI-nzgOB_@codewreck.org/ [2]: https://lore.kernel.org/all/20230705063315.3680666-1-jeffxu@google.com/ [3]: https://lore.kernel.org/Y5yS8wCnuYGLHMj4@x1n/ [4]: https://lore.kernel.org/f185bb42-b29c-977e-312e-3349eea15383@linuxfoundation.org/ This patch (of 5): Before this change, a test runner using this self test would see a return code of 0 when the tests using a child process (namely the MFD_NOEXEC_SEAL and MFD_EXEC tests) failed, masking test failures. Link: https://lkml.kernel.org/r/20230814-memfd-vm-noexec-uapi-fixes-v2-0-7ff9e3e10ba6@cyphar.com Link: https://lkml.kernel.org/r/20230814-memfd-vm-noexec-uapi-fixes-v2-1-7ff9e3e10ba6@cyphar.com Fixes: 11f75a01448f ("selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC") Signed-off-by: Aleksa Sarai Reviewed-by: Jeff Xu Cc: "Christian Brauner (Microsoft)" Cc: Daniel Verkamp Cc: Dominique Martinet Cc: Kees Cook Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED

2023-08-18T17:12:11+00:00

Add selftest for sysctl vm.memfd_noexec is 2 (MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) memfd_create(.., MFD_EXEC) should fail in this case. Link: https://lkml.kernel.org/r/20230705063315.3680666-3-jeffxu@google.com Reported-by: Dominique Martinet Closes: https://lore.kernel.org/linux-mm/CABi2SkXUX_QqTQ10Yx9bBUGpN1wByOi_=gZU6WEy5a8MaQY3Jw@mail.gmail.com/T/ Signed-off-by: Jeff Xu Cc: Daniel Verkamp Cc: Dmitry Torokhov Cc: Hugh Dickins Cc: Jann Horn Cc: Jorge Lucangeli Obes Cc: Kees Cook Cc: kernel test robot Cc: Mike Kravetz Cc: Shuah Khan Signed-off-by: Andrew Morton

selftests/memfd: fix test_sysctl

2023-04-18T23:53:52+00:00

sysctl memfd_noexec is pid-namespaced, non-reservable, and inherent to the child process. Move the inherence test from init ns to child ns, so init ns can keep the default value. Link: https://lkml.kernel.org/r/20230414022801.2545257-1-jeffxu@google.com Signed-off-by: Jeff Xu Reported-by: kernel test robot Link: https://lore.kernel.org/oe-lkp/202303312259.441e35db-yujie.liu@intel.com Tested-by: Yujie Liu Cc: Daniel Verkamp Cc: Dmitry Torokhov Cc: Hugh Dickins Cc: Jann Horn Cc: Jorge Lucangeli Obes Cc: Kees Cook Cc: Shuah Khan Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-02-24T01:09:35+00:00

Pull MM updates from Andrew Morton: - Daniel Verkamp has contributed a memfd series ("mm/memfd: add F_SEAL_EXEC") which permits the setting of the memfd execute bit at memfd creation time, with the option of sealing the state of the X bit. - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare") which addresses a rare race condition related to PMD unsharing. - Several folioification patch serieses from Matthew Wilcox, Vishal Moola, Sidhartha Kumar and Lorenzo Stoakes - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which does perform some memcg maintenance and cleanup work. - SeongJae Park has added DAMOS filtering to DAMON, with the series "mm/damon/core: implement damos filter". These filters provide users with finer-grained control over DAMOS's actions. SeongJae has also done some DAMON cleanup work. - Kairui Song adds a series ("Clean up and fixes for swap"). - Vernon Yang contributed the series "Clean up and refinement for maple tree". - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It adds to MGLRU an LRU of memcgs, to improve the scalability of global reclaim. - David Hildenbrand has added some userfaultfd cleanup work in the series "mm: uffd-wp + change_protection() cleanups". - Christoph Hellwig has removed the generic_writepages() library function in the series "remove generic_writepages". - Baolin Wang has performed some maintenance on the compaction code in his series "Some small improvements for compaction". - Sidhartha Kumar is doing some maintenance work on struct page in his series "Get rid of tail page fields". - David Hildenbrand contributed some cleanup, bugfixing and generalization of pte management and of pte debugging in his series "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs". - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation flag in the series "Discard __GFP_ATOMIC". - Sergey Senozhatsky has improved zsmalloc's memory utilization with his series "zsmalloc: make zspage chain size configurable". - Joey Gouly has added prctl() support for prohibiting the creation of writeable+executable mappings. The previous BPF-based approach had shortcomings. See "mm: In-kernel support for memory-deny-write-execute (MDWE)". - Waiman Long did some kmemleak cleanup and bugfixing in the series "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF". - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series "mm: multi-gen LRU: improve". - Jiaqi Yan has provided some enhancements to our memory error statistics reporting, mainly by presenting the statistics on a per-node basis. See the series "Introduce per NUMA node memory error statistics". - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog regression in compaction via his series "Fix excessive CPU usage during compaction". - Christoph Hellwig does some vmalloc maintenance work in the series "cleanup vfree and vunmap". - Christoph Hellwig has removed block_device_operations.rw_page() in ths series "remove ->rw_page". - We get some maple_tree improvements and cleanups in Liam Howlett's series "VMA tree type safety and remove __vma_adjust()". - Suren Baghdasaryan has done some work on the maintainability of our vm_flags handling in the series "introduce vm_flags modifier functions". - Some pagemap cleanup and generalization work in Mike Rapoport's series "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and "fixups for generic implementation of pfn_valid()" - Baoquan He has done some work to make /proc/vmallocinfo and /proc/kcore better represent the real state of things in his series "mm/vmalloc.c: allow vread() to read out vm_map_ram areas". - Jason Gunthorpe rationalized the GUP system's interface to the rest of the kernel in the series "Simplify the external interface for GUP". - SeongJae Park wishes to migrate people from DAMON's debugfs interface over to its sysfs interface. To support this, we'll temporarily be printing warnings when people use the debugfs interface. See the series "mm/damon: deprecate DAMON debugfs interface". - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes and clean-ups" series. - Huang Ying has provided a dramatic reduction in migration's TLB flush IPI rates with the series "migrate_pages(): batch TLB flushing". - Arnd Bergmann has some objtool fixups in "objtool warning fixes". * tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits) include/linux/migrate.h: remove unneeded externs mm/memory_hotplug: cleanup return value handing in do_migrate_range() mm/uffd: fix comment in handling pte markers mm: change to return bool for isolate_movable_page() mm: hugetlb: change to return bool for isolate_hugetlb() mm: change to return bool for isolate_lru_page() mm: change to return bool for folio_isolate_lru() objtool: add UACCESS exceptions for __tsan_volatile_read/write kmsan: disable ftrace in kmsan core code kasan: mark addr_has_metadata __always_inline mm: memcontrol: rename memcg_kmem_enabled() sh: initialize max_mapnr m68k/nommu: add missing definition of ARCH_PFN_OFFSET mm: percpu: fix incorrect size in pcpu_obj_full_size() maple_tree: reduce stack usage with gcc-9 and earlier mm: page_alloc: call panic() when memoryless node allocation fails mm: multi-gen LRU: avoid futile retries migrate_pages: move THP/hugetlb migration support check to simplify code migrate_pages: batch flushing TLB migrate_pages: share more code between _unmap and _move ...