The patch titled
Subject: pipe: simplify round_pipe_size()
has been added to the -mm tree. Its filename is
pipe-simplify-round_pipe_size.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/pipe-simplify-round_pipe_size.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/pipe-simplify-round_pipe_size.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Eric Biggers <ebiggers@xxxxxxxxxx>
Subject: 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@xxxxxxxxx
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Luis R . Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: Willy Tarreau <w@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/pipe.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff -puN fs/pipe.c~pipe-simplify-round_pipe_size fs/pipe.c
--- a/fs/pipe.c~pipe-simplify-round_pipe_size
+++ a/fs/pipe.c
@@ -1022,20 +1022,14 @@ const struct file_operations pipefifo_fo
*/
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_in
long ret = 0;
size = round_pipe_size(arg);
- if (size == 0)
- return -EINVAL;
nr_pages = size >> PAGE_SHIFT;
if (!nr_pages)
_
Patches currently in -mm which might be from ebiggers@xxxxxxxxxx are
userfaultfd-convert-to-use-anon_inode_getfd.patch
pipe-sysctl-drop-min-parameter-from-pipe-max-size-converter.patch
pipe-sysctl-remove-pipe_proc_fn.patch
pipe-actually-allow-root-to-exceed-the-pipe-buffer-limits.patch
pipe-fix-off-by-one-error-when-checking-buffer-limits.patch
pipe-reject-f_setpipe_sz-with-size-over-uint_max.patch
pipe-simplify-round_pipe_size.patch
pipe-read-buffer-limits-atomically.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
