The patch titled
Subject: mm: userfaultfd: check for start + len overflow in validate_range
has been added to the -mm mm-unstable branch. Its filename is
mm-userfaultfd-check-for-start-len-overflow-in-validate_range.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-userfaultfd-check-for-start-len-overflow-in-validate_range.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Subject: mm: userfaultfd: check for start + len overflow in validate_range
Date: Fri, 7 Jul 2023 14:55:34 -0700
Most userfaultfd ioctls take a `start + len` range as an argument. We
have the validate_range helper to check that such ranges are valid.
However, some (but not all!) ioctls *also* check that `start + len`
doesn't wrap around (overflow).
Just check for this in validate_range. This saves some repetitive code,
and adds the check to some ioctls which weren't bothering to check for it
before.
Link: https://lkml.kernel.org/r/20230707215540.2324998-3-axelrasmussen@xxxxxxxxxx
Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
Cc: Huang, Ying <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: James Houghton <jthoughton@xxxxxxxxxx>
Cc: Jan Alexander Steffens (heftig) <heftig@xxxxxxxxxxxxx>
Cc: Jiaqi Yan <jiaqiyan@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: T.J. Alumbaugh <talumbau@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: ZhangPeng <zhangpeng362@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)
--- a/fs/userfaultfd.c~mm-userfaultfd-check-for-start-len-overflow-in-validate_range
+++ a/fs/userfaultfd.c
@@ -1300,6 +1300,8 @@ static __always_inline int validate_rang
return -EINVAL;
if (len > task_size - start)
return -EINVAL;
+ if (start + len <= start)
+ return -EINVAL;
return 0;
}
@@ -1754,14 +1756,8 @@ static int userfaultfd_copy(struct userf
ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
if (ret)
goto out;
- /*
- * double check for wraparound just in case. copy_from_user()
- * will later check uffdio_copy.src + uffdio_copy.len to fit
- * in the userland range.
- */
+
ret = -EINVAL;
- if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src)
- goto out;
if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP))
goto out;
if (uffdio_copy.mode & UFFDIO_COPY_MODE_WP)
@@ -1921,11 +1917,6 @@ static int userfaultfd_continue(struct u
goto out;
ret = -EINVAL;
- /* double check for wraparound just in case. */
- if (uffdio_continue.range.start + uffdio_continue.range.len <=
- uffdio_continue.range.start) {
- goto out;
- }
if (uffdio_continue.mode & ~(UFFDIO_CONTINUE_MODE_DONTWAKE |
UFFDIO_CONTINUE_MODE_WP))
goto out;
_
Patches currently in -mm which might be from axelrasmussen@xxxxxxxxxx are
mm-make-pte_marker_swapin_error-more-general.patch
mm-userfaultfd-check-for-start-len-overflow-in-validate_range.patch
mm-userfaultfd-extract-file-size-check-out-into-a-helper.patch
mm-userfaultfd-add-new-uffdio_poison-ioctl.patch
mm-userfaultfd-support-uffdio_poison-for-hugetlbfs.patch
mm-userfaultfd-document-and-enable-new-uffdio_poison-feature.patch
selftests-mm-refactor-uffd_poll_thread-to-allow-custom-fault-handlers.patch
selftests-mm-add-uffd-unit-test-for-uffdio_poison.patch
