From 6de2aeffabaafaeda819e60ec8d04f199711e11a Mon Sep 17 00:00:00 2001 From: John Hubbard Date: Wed, 3 Jun 2026 19:53:14 -0700 Subject: [PATCH 1/2] libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo() Since commit 1e7ab6f67824 ("anon_inode: rework assertions"), path_noexec() warns when an anonymous-inode file is mmap'd from a superblock that has not set SB_I_NOEXEC. dma-buf backs its files this way and never set the flag, so mmap of any exported buffer trips the warning on a CONFIG_DEBUG_VFS=y kernel: WARNING: CPU: 11 PID: 121813 at fs/exec.c:118 path_noexec+0x47/0x50 do_mmap+0x2b5/0x680 vm_mmap_pgoff+0x129/0x210 ksys_mmap_pgoff+0x177/0x240 __x64_sys_mmap+0x33/0x70 init_pseudo() sets up internal SB_NOUSER mounts that are never path-reachable. Set both flags here so every pseudo filesystem gets them by default instead of each caller setting them. SB_I_NODEV is inert for unreachable mounts. SB_I_NOEXEC has one visible effect: an executable mapping of a pseudo-fs fd, such as a dma-buf, now fails with -EPERM, which is the invariant the assertion enforces. No in-tree caller maps these executable. Reproduce on CONFIG_DEBUG_VFS=y: make -C tools/testing/selftests/dmabuf-heaps sudo ./tools/testing/selftests/dmabuf-heaps/dmabuf-heap -t system Fixes: 1e7ab6f67824 ("anon_inode: rework assertions") Suggested-by: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: John Hubbard Link: https://patch.msgid.link/20260604025315.245910-2-jhubbard@nvidia.com Signed-off-by: Christian Brauner (Amutable) --- fs/libfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/libfs.c b/fs/libfs.c index 80a330c8296f..124139645f7f 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -736,6 +736,7 @@ struct pseudo_fs_context *init_pseudo(struct fs_context *fc, fc->fs_private = ctx; fc->ops = &pseudo_fs_context_ops; fc->sb_flags |= SB_NOUSER; + fc->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; fc->global = true; } return ctx; From be5748d2ae03907918298cc355bea73aed98ebc0 Mon Sep 17 00:00:00 2001 From: John Hubbard Date: Wed, 3 Jun 2026 19:53:15 -0700 Subject: [PATCH 2/2] libfs: drop redundant SB_I_NOEXEC/SB_I_NODEV in init_pseudo() callers init_pseudo() now sets SB_I_NOEXEC and SB_I_NODEV by default, so the per-caller assignments are redundant. Drop them. Signed-off-by: John Hubbard Link: https://patch.msgid.link/20260604025315.245910-3-jhubbard@nvidia.com Signed-off-by: Christian Brauner (Amutable) --- fs/aio.c | 1 - fs/anon_inodes.c | 2 -- fs/nsfs.c | 1 - fs/pidfs.c | 2 -- mm/secretmem.c | 2 -- virt/kvm/guest_memfd.c | 2 -- 6 files changed, 10 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 722476560848..f57fa21a2503 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -318,7 +318,6 @@ static int aio_init_fs_context(struct fs_context *fc) pfc = init_pseudo(fc, AIO_RING_MAGIC); if (!pfc) return -ENOMEM; - fc->s_iflags |= SB_I_NOEXEC; pfc->ops = &aio_super_operations; return 0; } diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index b8381c7fb636..a7b9b948e33d 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -86,8 +86,6 @@ static int anon_inodefs_init_fs_context(struct fs_context *fc) struct pseudo_fs_context *ctx = init_pseudo(fc, ANON_INODE_FS_MAGIC); if (!ctx) return -ENOMEM; - fc->s_iflags |= SB_I_NOEXEC; - fc->s_iflags |= SB_I_NODEV; ctx->dops = &anon_inodefs_dentry_operations; return 0; } diff --git a/fs/nsfs.c b/fs/nsfs.c index 51e8c9430477..c43c127cc035 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -664,7 +664,6 @@ static int nsfs_init_fs_context(struct fs_context *fc) struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC); if (!ctx) return -ENOMEM; - fc->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; ctx->s_d_flags |= DCACHE_DONTCACHE; ctx->ops = &nsfs_ops; ctx->eops = &nsfs_export_operations; diff --git a/fs/pidfs.c b/fs/pidfs.c index 1cce4f34a051..c363416766f1 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -1115,8 +1115,6 @@ static int pidfs_init_fs_context(struct fs_context *fc) if (!ctx) return -ENOMEM; - fc->s_iflags |= SB_I_NOEXEC; - fc->s_iflags |= SB_I_NODEV; ctx->s_d_flags |= DCACHE_DONTCACHE; ctx->ops = &pidfs_sops; ctx->eops = &pidfs_export_operations; diff --git a/mm/secretmem.c b/mm/secretmem.c index 5f57ac4720d3..4877c262cb1f 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -245,8 +245,6 @@ static int secretmem_init_fs_context(struct fs_context *fc) if (!ctx) return -ENOMEM; - fc->s_iflags |= SB_I_NOEXEC; - fc->s_iflags |= SB_I_NODEV; return 0; } diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 69c9d6d546b2..80f201035d77 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -973,8 +973,6 @@ static int kvm_gmem_init_fs_context(struct fs_context *fc) if (!init_pseudo(fc, GUEST_MEMFD_MAGIC)) return -ENOMEM; - fc->s_iflags |= SB_I_NOEXEC; - fc->s_iflags |= SB_I_NODEV; ctx = fc->fs_private; ctx->ops = &kvm_gmem_super_operations;