diff options
| author | Eric Biggers | 2018-02-06 15:42:05 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2018-02-06 18:32:48 -0800 |
| commit | c4fed5a91fadc8a277b1eda474317b501651dd3e (patch) | |
| tree | 6194bd7d003a2527f675dee2ab3fbb03332a8e19 | |
| parent | 96e99be40e4cff870a83233731121ec0f7f95075 (diff) | |
pipe: simplify round_pipe_size()
round_pipe_size() calculates the number of pages the requested size
corresponds to, then rounds the page count up to the next power of 2.
However, it also rounds everything < PAGE_SIZE up to PAGE_SIZE.
Therefore, there's no need to actually translate the size into a page
count; we just need to round the size up to the next power of 2.
We do need to verify the size isn't greater than (1 << 31), since on
32-bit systems roundup_pow_of_two() would be undefined in that case. But
that can just be combined with the UINT_MAX check which we need anyway
now.
Finally, update pipe_set_size() to not redundantly check the return value
of round_pipe_size() for the "invalid size" case twice.
Link: http://lkml.kernel.org/r/20180111052902.14409-7-ebiggers3@gmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/pipe.c | 14 |
1 files changed, 3 insertions, 11 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 817393d36244..8be52158c400 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -1022,20 +1022,14 @@ const struct file_operations pipefifo_fops = { */ unsigned int round_pipe_size(unsigned long size) { - unsigned long nr_pages; - - if (size > UINT_MAX) + if (size > (1U << 31)) return 0; /* Minimum pipe size, as required by POSIX */ if (size < PAGE_SIZE) - size = PAGE_SIZE; - - nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; - if (nr_pages == 0) - return 0; + return PAGE_SIZE; - return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; + return roundup_pow_of_two(size); } /* @@ -1050,8 +1044,6 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) long ret = 0; size = round_pipe_size(arg); - if (size == 0) - return -EINVAL; nr_pages = size >> PAGE_SHIFT; if (!nr_pages) |