[ 15/48] splice: Apply generic position and size checks to each write

From: Willy Tarreau
Date: Fri May 15 2015 - 04:27:07 EST


2.6.32-longterm review patch. If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
fs/ocfs2/file.c | 8 ++++++--
fs/splice.c | 8 ++++++--
2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index de059f4..6aede32 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2081,9 +2081,7 @@ static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
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,
};

@@ -2092,6 +2090,12 @@ static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
out->f_path.dentry->d_name.len,
out->f_path.dentry->d_name.name);

+ ret = generic_write_checks(out, ppos, &len, 0);
+ if (ret)
+ return ret;
+ sd.total_len = len;
+ sd.pos = *ppos;
+
if (pipe->inode)
mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_PARENT);

diff --git a/fs/splice.c b/fs/splice.c
index cdad986..1ef1c00 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -945,13 +945,17 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
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);
--
1.7.12.2.21.g234cd45.dirty



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/