diff options
| author | David Laight <david.laight.linux@gmail.com> | 2025-02-09 17:47:11 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-03-16 22:06:10 -0700 |
| commit | c2661f5fe888c14eb1f09ed23e74213366fa70f3 (patch) | |
| tree | dac63e0650c6a3a6106c0db00a25c7440876dc04 /mm/gup.c | |
| parent | 67254c7d70b63797a54173fbe05cd6552aca11d4 (diff) | |
mm: remove the access_ok() call from gup_fast_fallback()
Historiaclly the code relied on access_ok() to validate the address range.
Commit 26f4c328079d7 added an explicit wrap check before access_ok().
Commit c28b1fc70390d then changed the wrap test to use check_add_overflow().
Commit 6014bc27561f2 relaxed the checks in x86-64's access_ok() and added
an explicit check for TASK_SIZE here to make up for it.
That left a pointless access_ok() call with its associated 'lfence' that
can never actually fail.
So just delete the test.
Link: https://lkml.kernel.org/r/20250209174711.60889-1-david.laight.linux@gmail.com
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirks^H^Hski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
| -rw-r--r-- | mm/gup.c | 4 |
1 files changed, 1 insertions, 3 deletions
@@ -2760,7 +2760,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * * *) ptes can be read atomically by the architecture. * - * *) access_ok is sufficient to validate userspace address ranges. + * *) valid user addesses are below TASK_MAX_SIZE * * The last two assumptions can be relaxed by the addition of helper functions. * @@ -3414,8 +3414,6 @@ static int gup_fast_fallback(unsigned long start, unsigned long nr_pages, return -EOVERFLOW; if (end > TASK_SIZE_MAX) return -EFAULT; - if (unlikely(!access_ok((void __user *)start, len))) - return -EFAULT; nr_pinned = gup_fast(start, end, gup_flags, pages); if (nr_pinned == nr_pages || gup_flags & FOLL_FAST_ONLY) |