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UPSTREAM: binder: Use kmap_local_page() in binder_alloc_copy_user_to_buffer()

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The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible. With kmap_local_page(), the mapping is per
thread, CPU local and not globally visible.

binder_alloc_copy_user_to_buffer() is a function where the use of
kmap_local_page() in place of kmap() is correctly suited because
the mapping is local to the thread.

Therefore, use kmap_local_page() / kunmap_local().

Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220425175754.8180-3-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 365876437
Bug: 367895677
(cherry picked from commit 1d625960e4)
Change-Id: I49739365cf5dcf584be1aab0c93848aa9ce886a8
Signed-off-by: Carlos Llamas <cmllamas@google.com>
This commit is contained in:
Fabio M. De Francesco
2022-04-25 19:57:53 +02:00
committed by Dongjin Kim
parent 88e297173c
commit e38087f053
1 changed files with 2 additions and 2 deletions
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4
drivers/android/binder_alloc.c
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@@ -1247,9 +1247,9 @@ binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
page = binder_alloc_get_page(alloc, buffer,
buffer_offset, &pgoff);
size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
kptr = kmap(page) + pgoff;
kptr = kmap_local_page(page) + pgoff;
ret = copy_from_user(kptr, from, size);
kunmap(page);
kunmap_local(kptr);
if (ret)
return bytes - size + ret;
bytes -= size;