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fix a kmap leak in virtio_console

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While we are at it, don't do kmap() under kmap_atomic(), *especially*
for a page we'd allocated with GFP_KERNEL.  It's spelled "page_address",
and had that been more than that, we'd have a real trouble - kmap_high()
can block, and doing that while holding kmap_atomic() is a Bad Idea(tm).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-02-02 07:05:05 -05:00
parent d311d79de3
commit c9efe51165
1 changed files with 3 additions and 6 deletions
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9
drivers/char/virtio_console.c
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@ -890,12 +890,10 @@ static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
} else {
/* Failback to copying a page */
struct page *page = alloc_page(GFP_KERNEL);
char *src = buf->ops->map(pipe, buf, 1);
char *dst;
char *src;
if (!page)
return -ENOMEM;
dst = kmap(page);
offset = sd->pos & ~PAGE_MASK;
@ -903,9 +901,8 @@ static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
if (len + offset > PAGE_SIZE)
len = PAGE_SIZE - offset;
memcpy(dst + offset, src + buf->offset, len);
kunmap(page);
src = buf->ops->map(pipe, buf, 1);
memcpy(page_address(page) + offset, src + buf->offset, len);
buf->ops->unmap(pipe, buf, src);
sg_set_page(&(sgl->sg[sgl->n]), page, len, offset);