[PATCH 3.14 14/34] splice: Apply generic position and size checks to each write

Greg Kroah-Hartman
2015-07-01T18:46:33Z

From: Ben Hutchings <ben@decadent.org.uk>

commit 894c6350eaad7e613ae267504014a456e00a3e2a from the 3.2-stable branch.

We need to check the position and size of file writes against various
limits, using generic_write_check(). This was not being done for
the splice write path. It was fixed upstream by commit 8d0207652cbe
("->splice_write() via ->write_iter()") but we can't apply that.

CVE-2014-7822

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Vinson Lee <vlee@twopensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ocfs2/file.c | 8 ++++++--
fs/splice.c | 8 ++++++--
2 files changed, 12 insertions(+), 4 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2478,9 +2478,7 @@ static ssize_t ocfs2_file_splice_write(s
struct address_space *mapping = out->f_mapping;
struct inode *inode = mapping->host;
struct splice_desc sd = {
- .total_len = len,
.flags = flags,
- .pos = *ppos,
.u.file = out,
};

@@ -2490,6 +2488,12 @@ static ssize_t ocfs2_file_splice_write(s
out->f_path.dentry->d_name.len,
out->f_path.dentry->d_name.name, len);

+ ret = generic_write_checks(out, ppos, &len, 0);
+ if (ret)
+ return ret;
+ sd.total_len = len;
+ sd.pos = *ppos;
+
pipe_lock(pipe);

splice_from_pipe_begin(&sd);
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1012,13 +1012,17 @@ generic_file_splice_write(struct pipe_in
struct address_space *mapping = out->f_mapping;
struct inode *inode = mapping->host;
struct splice_desc sd = {
- .total_len = len,
.flags = flags,
- .pos = *ppos,
.u.file = out,
};
ssize_t ret;

+ ret = generic_write_checks(out, ppos, &len, S_ISBLK(inode->i_mode));
+ if (ret)
+ return ret;
+ sd.total_len = len;
+ sd.pos = *ppos;
+
pipe_lock(pipe);

splice_from_pipe_begin(&sd);