vfs: missed source of ->f_pos races
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@zeniv.linux.org.uk>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/compat.c b/fs/compat.c
index 6161255..1bdb350 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1155,11 +1155,14 @@
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;
}
@@ -1221,11 +1224,14 @@
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;
}