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authorPeter Xu <peterx@redhat.com>2021-05-14 17:27:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-14 19:41:32 -0700
commit22247efd822e6d263f3c8bd327f3f769aea9b1d9 (patch)
tree2bc99fea483cdffe7a0e114b629ab194c5aec04f /fs
parentbd3c9cdb21a2674dd0db70199df884828e37abd4 (diff)
mm/hugetlb: fix F_SEAL_FUTURE_WRITE
Patch series "mm/hugetlb: Fix issues on file sealing and fork", v2. Hugh reported issue with F_SEAL_FUTURE_WRITE not applied correctly to hugetlbfs, which I can easily verify using the memfd_test program, which seems that the program is hardly run with hugetlbfs pages (as by default shmem). Meanwhile I found another probably even more severe issue on that hugetlb fork won't wr-protect child cow pages, so child can potentially write to parent private pages. Patch 2 addresses that. After this series applied, "memfd_test hugetlbfs" should start to pass. This patch (of 2): F_SEAL_FUTURE_WRITE is missing for hugetlb starting from the first day. There is a test program for that and it fails constantly. $ ./memfd_test hugetlbfs memfd-hugetlb: CREATE memfd-hugetlb: BASIC memfd-hugetlb: SEAL-WRITE memfd-hugetlb: SEAL-FUTURE-WRITE mmap() didn't fail as expected Aborted (core dumped) I think it's probably because no one is really running the hugetlbfs test. Fix it by checking FUTURE_WRITE also in hugetlbfs_file_mmap() as what we do in shmem_mmap(). Generalize a helper for that. Link: https://lkml.kernel.org/r/20210503234356.9097-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20210503234356.9097-2-peterx@redhat.com Fixes: ab3948f58ff84 ("mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd") Signed-off-by: Peter Xu <peterx@redhat.com> Reported-by: Hugh Dickins <hughd@google.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/hugetlbfs/inode.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index a2a42335e8fd..9d9e0097c1d3 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -131,6 +131,7 @@ static void huge_pagevec_release(struct pagevec *pvec)
static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file_inode(file);
+ struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
loff_t len, vma_len;
int ret;
struct hstate *h = hstate_file(file);
@@ -146,6 +147,10 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
vma->vm_ops = &hugetlb_vm_ops;
+ ret = seal_check_future_write(info->seals, vma);
+ if (ret)
+ return ret;
+
/*
* page based offset in vm_pgoff could be sufficiently large to
* overflow a loff_t when converted to byte offset. This can