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userfaultfd: untag user pointers

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This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

userfaultfd code use provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in validate_range().

Link: http://lkml.kernel.org/r/cdc59ddd7011012ca2e689bc88c3b65b1ea7e413.1563904656.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2019-09-25 16:48:44 -07:00 committed by Linus Torvalds
parent ed8a66b832
commit 7d0325749a
1 changed files with 12 additions and 10 deletions
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22
fs/userfaultfd.c
View file

@ -1272,21 +1272,23 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
}
static __always_inline int validate_range(struct mm_struct *mm,
__u64 start, __u64 len)
__u64 *start, __u64 len)
{
__u64 task_size = mm->task_size;
if (start & ~PAGE_MASK)
*start = untagged_addr(*start);
if (*start & ~PAGE_MASK)
return -EINVAL;
if (len & ~PAGE_MASK)
return -EINVAL;
if (!len)
return -EINVAL;
if (start < mmap_min_addr)
if (*start < mmap_min_addr)
return -EINVAL;
if (start >= task_size)
if (*start >= task_size)
return -EINVAL;
if (len > task_size - start)
if (len > task_size - *start)
return -EINVAL;
return 0;
}
@ -1336,7 +1338,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
goto out;
}
ret = validate_range(mm, uffdio_register.range.start,
ret = validate_range(mm, &uffdio_register.range.start,
uffdio_register.range.len);
if (ret)
goto out;
@ -1525,7 +1527,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
goto out;
ret = validate_range(mm, uffdio_unregister.start,
ret = validate_range(mm, &uffdio_unregister.start,
uffdio_unregister.len);
if (ret)
goto out;
@ -1676,7 +1678,7 @@ static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
goto out;
ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len);
ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
if (ret)
goto out;
@ -1716,7 +1718,7 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
sizeof(uffdio_copy)-sizeof(__s64)))
goto out;
ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
if (ret)
goto out;
/*
@ -1772,7 +1774,7 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
sizeof(uffdio_zeropage)-sizeof(__s64)))
goto out;
ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
uffdio_zeropage.range.len);
if (ret)
goto out;