diff mbox series

[13/31] iov_iter_get_pages(): sanity-check arguments

Message ID	20220618053538.359065-14-viro@zeniv.linux.org.uk (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-fsdevel-owner@kernel.org> From: Al Viro <viro@zeniv.linux.org.uk> To: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>, Matthew Wilcox <willy@infradead.org> Subject: [PATCH 13/31] iov_iter_get_pages(): sanity-check arguments Date: Sat, 18 Jun 2022 06:35:20 +0100 Message-Id: <20220618053538.359065-14-viro@zeniv.linux.org.uk> In-Reply-To: <20220618053538.359065-1-viro@zeniv.linux.org.uk> References: <Yq1iNHboD+9fz60M@ZenIV> <20220618053538.359065-1-viro@zeniv.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: Al Viro <viro@ftp.linux.org.uk> Precedence: bulk
Series	[01/31] splice: stop abusing iov_iter_advance() to flush a pipe \| expand [01/31] splice: stop abusing iov_iter_advance() to flush a pipe [02/31] ITER_PIPE: helper for getting pipe buffer by index [03/31] ITER_PIPE: helpers for adding pipe buffers [04/31] ITER_PIPE: allocate buffers as we go in copy-to-pipe primitives [05/31] ITER_PIPE: fold push_pipe() into __pipe_get_pages() [06/31] ITER_PIPE: lose iter_head argument of __pipe_get_pages() [07/31] ITER_PIPE: clean pipe_advance() up [08/31] ITER_PIPE: clean iov_iter_revert() [09/31] ITER_PIPE: cache the type of last buffer [10/31] ITER_PIPE: fold data_start() and pipe_space_for_user() together [11/31] iov_iter_get_pages{,_alloc}(): cap the maxsize with LONG_MAX [12/31] iov_iter_get_pages_alloc(): lift freeing pages array on failure exits into wrapper [13/31] iov_iter_get_pages(): sanity-check arguments [14/31] unify pipe_get_pages() and pipe_get_pages_alloc() [15/31] unify xarray_get_pages() and xarray_get_pages_alloc() [16/31] unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts [17/31] ITER_XARRAY: don't open-code DIV_ROUND_UP() [18/31] iov_iter: lift dealing with maxpages out of first_{iovec,bvec}_segment() [19/31] iov_iter: massage calling conventions for first_{iovec,bvec}_segment() [20/31] found_iovec_segment(): just return address [21/31] fold __pipe_get_pages() into pipe_get_pages() [22/31] iov_iter: saner helper for page array allocation [23/31] iov_iter: advancing variants of iov_iter_get_pages{,_alloc}() [24/31] block: convert to advancing variants of iov_iter_get_pages{,_alloc}() [25/31] iter_to_pipe(): switch to advancing variant of iov_iter_get_pages() [26/31] af_alg_make_sg(): switch to advancing variant of iov_iter_get_pages() [27/31] 9p: convert to advancing variant of iov_iter_get_pages_alloc() [28/31] ceph: switch the last caller of iov_iter_get_pages_alloc() [29/31] get rid of non-advancing variants [30/31] pipe_get_pages(): switch to append_pipe() [31/31] expand those iov_iter_advance()...

Commit Message

Al Viro June 18, 2022, 5:35 a.m. UTC

zero maxpages is bogus, but best treated as "just return 0";
NULL pages, OTOH, should be treated as a hard bug.

get rid of now completely useless checks in xarray_get_pages{,_alloc}().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 lib/iov_iter.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

Comments

Al Viro June 19, 2022, 3:07 a.m. UTC | #1

On Sat, Jun 18, 2022 at 06:35:20AM +0100, Al Viro wrote:

> +	if (!maxsize || maxpages)

	if (!maxsize || !maxpages)

obviously...  That's only a bisect hazard, since 16/31 fixes it.

diff mbox series

Patch

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index f5e14535f6bb..369fbb10b16f 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1271,9 +1271,6 @@  static ssize_t iter_xarray_get_pages(struct iov_iter *i,
 	size_t size = maxsize;
 	loff_t pos;
 
-	if (!size || !maxpages)
-		return 0;
-
 	pos = i->xarray_start + i->iov_offset;
 	index = pos >> PAGE_SHIFT;
 	offset = pos & ~PAGE_MASK;
@@ -1365,10 +1362,11 @@  ssize_t iov_iter_get_pages(struct iov_iter *i,
 
 	if (maxsize > i->count)
 		maxsize = i->count;
-	if (!maxsize)
+	if (!maxsize || maxpages)
 		return 0;
 	if (maxsize > LONG_MAX)
 		maxsize = LONG_MAX;
+	BUG_ON(!pages);
 
 	if (likely(user_backed_iter(i))) {
 		unsigned int gup_flags = 0;
@@ -1441,9 +1439,6 @@  static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
 	size_t size = maxsize;
 	loff_t pos;
 
-	if (!size)
-		return 0;
-
 	pos = i->xarray_start + i->iov_offset;
 	index = pos >> PAGE_SHIFT;
 	offset = pos & ~PAGE_MASK;