[ 128/180] vfs: missed source of ->f_pos races

[Willy Tarreau]

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

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

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 0e665d5d1125f9f4ccff56a75e814f10f88861a2 upstream.

compat_sys_{read,write}v() need the same "pass a copy of file->f_pos" thing
as sys_{read,write}{,v}().

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 fs/compat.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/compat.c b/fs/compat.c
index d1e2411..46b93d1 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1208,11 +1208,14 @@ compat_sys_readv(unsigned long fd, const struct compat_iovec __user *vec,
 	struct file *file;
 	int fput_needed;
 	ssize_t ret;
+	loff_t pos;
 
 	file = fget_light(fd, &fput_needed);
 	if (!file)
 		return -EBADF;
-	ret = compat_readv(file, vec, vlen, &file->f_pos);
+	pos = file->f_pos;
+	ret = compat_readv(file, vec, vlen, &pos);
+	file->f_pos = pos;
 	fput_light(file, fput_needed);
 	return ret;
 }
@@ -1265,11 +1268,14 @@ compat_sys_writev(unsigned long fd, const struct compat_iovec __user *vec,
 	struct file *file;
 	int fput_needed;
 	ssize_t ret;
+	loff_t pos;
 
 	file = fget_light(fd, &fput_needed);
 	if (!file)
 		return -EBADF;
-	ret = compat_writev(file, vec, vlen, &file->f_pos);
+	pos = file->f_pos;
+	ret = compat_writev(file, vec, vlen, &pos);
+	file->f_pos = pos;
 	fput_light(file, fput_needed);
 	return ret;
 }
-- 
1.7.2.1.45.g54fbc



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