From: Pavel Begunkov asml.silence@gmail.com
mainline inclusion from mainline-v5.12-rc1 commit 0f1d344feb534555a0dcd0beafb7211a37c5355e category: bugfix bugzilla: 188445,https://gitee.com/openeuler/kernel/issues/I6J5NZ
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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iter_file_splice_write() may spawn bvec segments with zero-length. In preparation for prohibiting them, filter out by hand at splice level.
Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Pavel Begunkov asml.silence@gmail.com Reviewed-by: Ming Lei ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Yang Erkun yangerkun@huawei.com Reviewed-by: Zhang Yi yi.zhang@huawei.com Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- fs/splice.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c index 866d5c2367b2..474fb8b5562a 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -662,12 +662,14 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
/* build the vector */ left = sd.total_len; - for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++, n++) { + for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) { struct pipe_buffer *buf = &pipe->bufs[tail & mask]; size_t this_len = buf->len;
- if (this_len > left) - this_len = left; + /* zero-length bvecs are not supported, skip them */ + if (!this_len) + continue; + this_len = min(this_len, left);
ret = pipe_buf_confirm(pipe, buf); if (unlikely(ret)) { @@ -680,6 +682,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, array[n].bv_len = this_len; array[n].bv_offset = buf->offset; left -= this_len; + n++; }
iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left);