The patch titled Subject: Fix userfaultfd_api to return EINVAL as expected has been added to the -mm mm-hotfixes-unstable branch. Its filename is fix-userfaultfd_api-to-return-einval-as-expected.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fix-userfaultfd_api-to-return-einval-as-expected.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Audra Mitchell <audra@xxxxxxxxxx> Subject: Fix userfaultfd_api to return EINVAL as expected Date: Wed, 26 Jun 2024 09:05:11 -0400 Currently if we request a feature that is not set in the Kernel config we fail silently and return all the available features. However, the man page indicates we should return an EINVAL. We need to fix this issue since we can end up with a Kernel warning should a program request the feature UFFD_FEATURE_WP_UNPOPULATED on a kernel with the config not set with this feature. [ 200.812896] WARNING: CPU: 91 PID: 13634 at mm/memory.c:1660 zap_pte_range+0x43d/0x660 [ 200.820738] Modules linked in: [ 200.869387] CPU: 91 PID: 13634 Comm: userfaultfd Kdump: loaded Not tainted 6.9.0-rc5+ #8 [ 200.877477] Hardware name: Dell Inc. PowerEdge R6525/0N7YGH, BIOS 2.7.3 03/30/2022 [ 200.885052] RIP: 0010:zap_pte_range+0x43d/0x660 Link: https://lkml.kernel.org/r/20240626130513.120193-1-audra@xxxxxxxxxx Fixes: e06f1e1dd499 ("userfaultfd: wp: enabled write protection in userfaultfd API") Signed-off-by: Audra Mitchell <audra@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Christian Brauner <brauner@xxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Cc: Peter Xu <peterx@xxxxxxxxxx> Cc: Rafael Aquini <raquini@xxxxxxxxxx> Cc: Shaohua Li <shli@xxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/userfaultfd.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/userfaultfd.c~fix-userfaultfd_api-to-return-einval-as-expected +++ a/fs/userfaultfd.c @@ -2057,7 +2057,7 @@ static int userfaultfd_api(struct userfa goto out; features = uffdio_api.features; ret = -EINVAL; - if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) + if (uffdio_api.api != UFFD_API) goto err_out; ret = -EPERM; if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE)) @@ -2081,6 +2081,11 @@ static int userfaultfd_api(struct userfa uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED; uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC; #endif + + ret = -EINVAL; + if (features & ~uffdio_api.features) + goto err_out; + uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) _ Patches currently in -mm which might be from audra@xxxxxxxxxx are fix-userfaultfd_api-to-return-einval-as-expected.patch