From: Miklos Szeredi <[email protected]>

Commit 6130f5315ee8 "switch vmsplice_to_user() to copy_page_to_iter()" in
v3.15-rc1 broke vmsplice(2).

This patch fixes two bugs:

 - count is not initialized to a proper value, which resulted in no data
   being copied

 - if rw_copy_check_uvector() returns negative then the iov might be leaked.

Tested OK.

Signed-off-by: Miklos Szeredi <[email protected]>
---
 fs/splice.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1537,7 +1537,7 @@ static long vmsplice_to_user(struct file
        struct iovec iovstack[UIO_FASTIOV];
        struct iovec *iov = iovstack;
        struct iov_iter iter;
-       ssize_t count = 0;
+       ssize_t count;
 
        pipe = get_pipe_info(file);
        if (!pipe)
@@ -1546,8 +1546,9 @@ static long vmsplice_to_user(struct file
        ret = rw_copy_check_uvector(READ, uiov, nr_segs,
                                    ARRAY_SIZE(iovstack), iovstack, &iov);
        if (ret <= 0)
-               return ret;
+               goto out;
 
+       count = ret;
        iov_iter_init(&iter, iov, nr_segs, count, 0);
 
        sd.len = 0;
@@ -1560,6 +1561,7 @@ static long vmsplice_to_user(struct file
        ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
        pipe_unlock(pipe);
 
+out:
        if (iov != iovstack)
                kfree(iov);
 
--
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