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Date: Mon, 31 Mar 2014 00:23:35 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org, "Al Viro" <viro@...iv.linux.org.uk>,
"Miklos Szeredi" <mszeredi@...e.cz>
Subject: [PATCH 3.2 050/200] fuse: fix pipe_buf_operations
3.2.56-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Miklos Szeredi <mszeredi@...e.cz>
commit 28a625cbc2a14f17b83e47ef907b2658576a32aa upstream.
Having this struct in module memory could Oops when if the module is
unloaded while the buffer still persists in a pipe.
Since sock_pipe_buf_ops is essentially the same as fuse_dev_pipe_buf_steal
merge them into nosteal_pipe_buf_ops (this is the same as
default_pipe_buf_ops except stealing the page from the buffer is not
allowed).
Reported-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
fs/fuse/dev.c | 22 +++++-----------------
fs/splice.c | 18 ++++++++++++++++++
include/linux/pipe_fs_i.h | 2 ++
net/core/skbuff.c | 32 +-------------------------------
4 files changed, 26 insertions(+), 48 deletions(-)
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1199,22 +1199,6 @@ static ssize_t fuse_dev_read(struct kioc
return fuse_dev_do_read(fc, file, &cs, iov_length(iov, nr_segs));
}
-static int fuse_dev_pipe_buf_steal(struct pipe_inode_info *pipe,
- struct pipe_buffer *buf)
-{
- return 1;
-}
-
-static const struct pipe_buf_operations fuse_dev_pipe_buf_ops = {
- .can_merge = 0,
- .map = generic_pipe_buf_map,
- .unmap = generic_pipe_buf_unmap,
- .confirm = generic_pipe_buf_confirm,
- .release = generic_pipe_buf_release,
- .steal = fuse_dev_pipe_buf_steal,
- .get = generic_pipe_buf_get,
-};
-
static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe,
size_t len, unsigned int flags)
@@ -1261,7 +1245,11 @@ static ssize_t fuse_dev_splice_read(stru
buf->page = bufs[page_nr].page;
buf->offset = bufs[page_nr].offset;
buf->len = bufs[page_nr].len;
- buf->ops = &fuse_dev_pipe_buf_ops;
+ /*
+ * Need to be careful about this. Having buf->ops in module
+ * code can Oops if the buffer persists after module unload.
+ */
+ buf->ops = &nosteal_pipe_buf_ops;
pipe->nrbufs++;
page_nr++;
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -554,6 +554,24 @@ static const struct pipe_buf_operations
.get = generic_pipe_buf_get,
};
+static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ return 1;
+}
+
+/* Pipe buffer operations for a socket and similar. */
+const struct pipe_buf_operations nosteal_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = generic_pipe_buf_release,
+ .steal = generic_pipe_buf_nosteal,
+ .get = generic_pipe_buf_get,
+};
+EXPORT_SYMBOL(nosteal_pipe_buf_ops);
+
static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
unsigned long vlen, loff_t offset)
{
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -160,6 +160,8 @@ int generic_pipe_buf_confirm(struct pipe
int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
+extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
+
/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
struct pipe_inode_info *get_pipe_info(struct file *file);
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -74,36 +74,6 @@
static struct kmem_cache *skbuff_head_cache __read_mostly;
static struct kmem_cache *skbuff_fclone_cache __read_mostly;
-static void sock_pipe_buf_release(struct pipe_inode_info *pipe,
- struct pipe_buffer *buf)
-{
- put_page(buf->page);
-}
-
-static void sock_pipe_buf_get(struct pipe_inode_info *pipe,
- struct pipe_buffer *buf)
-{
- get_page(buf->page);
-}
-
-static int sock_pipe_buf_steal(struct pipe_inode_info *pipe,
- struct pipe_buffer *buf)
-{
- return 1;
-}
-
-
-/* Pipe buffer operations for a socket. */
-static const struct pipe_buf_operations sock_pipe_buf_ops = {
- .can_merge = 0,
- .map = generic_pipe_buf_map,
- .unmap = generic_pipe_buf_unmap,
- .confirm = generic_pipe_buf_confirm,
- .release = sock_pipe_buf_release,
- .steal = sock_pipe_buf_steal,
- .get = sock_pipe_buf_get,
-};
-
/*
* Keep out-of-line to prevent kernel bloat.
* __builtin_return_address is not used because it is not always
@@ -1665,7 +1635,7 @@ int skb_splice_bits(struct sk_buff *skb,
.partial = partial,
.nr_pages_max = MAX_SKB_FRAGS,
.flags = flags,
- .ops = &sock_pipe_buf_ops,
+ .ops = &nosteal_pipe_buf_ops,
.spd_release = sock_spd_release,
};
struct sk_buff *frag_iter;
--
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