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authorMiklos Szeredi <mszeredi@suse.cz>2014-09-24 17:09:11 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2014-09-26 21:16:51 -0400
commit2c80929c4c4d54e568b07ab85877d5fd38f4b02f (patch)
treea43d1f9a9706d519a46c1b772b69c8996319961c
parentb928095b0a7cff7fb9fcf4c706348ceb8ab2c295 (diff)
downloadlinux-linaro-stable-2c80929c4c4d54e568b07ab85877d5fd38f4b02f.tar.gz
fuse: honour max_read and max_write in direct_io mode
The third argument of fuse_get_user_pages() "nbytesp" refers to the number of bytes a caller asked to pack into fuse request. This value may be lesser than capacity of fuse request or iov_iter. So fuse_get_user_pages() must ensure that *nbytesp won't grow. Now, when helper iov_iter_get_pages() performs all hard work of extracting pages from iov_iter, it can be done by passing properly calculated "maxsize" to the helper. The other caller of iov_iter_get_pages() (dio_refill_pages()) doesn't need this capability, so pass LONG_MAX as the maxsize argument here. Fixes: c9c37e2e6378 ("fuse: switch to iov_iter_get_pages()") Reported-by: Werner Baumann <werner.baumann@onlinehome.de> Tested-by: Maxim Patlasov <mpatlasov@parallels.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/direct-io.c2
-rw-r--r--fs/fuse/file.c1
-rw-r--r--include/linux/uio.h2
-rw-r--r--mm/iov_iter.c14
4 files changed, 12 insertions, 7 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index c3116404ab49..e181b6b2e297 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -158,7 +158,7 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
{
ssize_t ret;
- ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES,
+ ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES,
&sdio->from);
if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) {
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 912061ac4baf..caa8d95b24e8 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1305,6 +1305,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
size_t start;
ssize_t ret = iov_iter_get_pages(ii,
&req->pages[req->num_pages],
+ *nbytesp - nbytes,
req->max_pages - req->num_pages,
&start);
if (ret < 0)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 48d64e6ab292..290fbf0b6b8a 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -84,7 +84,7 @@ unsigned long iov_iter_alignment(const struct iov_iter *i);
void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
unsigned long nr_segs, size_t count);
ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
- unsigned maxpages, size_t *start);
+ size_t maxsize, unsigned maxpages, size_t *start);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages);
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index ab88dc0ea1d3..9a09f2034fcc 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -310,7 +310,7 @@ void iov_iter_init(struct iov_iter *i, int direction,
EXPORT_SYMBOL(iov_iter_init);
static ssize_t get_pages_iovec(struct iov_iter *i,
- struct page **pages, unsigned maxpages,
+ struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
size_t offset = i->iov_offset;
@@ -323,6 +323,8 @@ static ssize_t get_pages_iovec(struct iov_iter *i,
len = iov->iov_len - offset;
if (len > i->count)
len = i->count;
+ if (len > maxsize)
+ len = maxsize;
addr = (unsigned long)iov->iov_base + offset;
len += *start = addr & (PAGE_SIZE - 1);
if (len > maxpages * PAGE_SIZE)
@@ -588,13 +590,15 @@ static unsigned long alignment_bvec(const struct iov_iter *i)
}
static ssize_t get_pages_bvec(struct iov_iter *i,
- struct page **pages, unsigned maxpages,
+ struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
const struct bio_vec *bvec = i->bvec;
size_t len = bvec->bv_len - i->iov_offset;
if (len > i->count)
len = i->count;
+ if (len > maxsize)
+ len = maxsize;
/* can't be more than PAGE_SIZE */
*start = bvec->bv_offset + i->iov_offset;
@@ -711,13 +715,13 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
EXPORT_SYMBOL(iov_iter_alignment);
ssize_t iov_iter_get_pages(struct iov_iter *i,
- struct page **pages, unsigned maxpages,
+ struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
if (i->type & ITER_BVEC)
- return get_pages_bvec(i, pages, maxpages, start);
+ return get_pages_bvec(i, pages, maxsize, maxpages, start);
else
- return get_pages_iovec(i, pages, maxpages, start);
+ return get_pages_iovec(i, pages, maxsize, maxpages, start);
}
EXPORT_SYMBOL(iov_iter_get_pages);