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fs: prevent page refcount overflow in pipe_buf_get

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Change pipe_buf_get() to return a bool indicating whether it succeeded
in raising the refcount of the page (if the thing in the pipe is a page).
This removes another mechanism for overflowing the page refcount.  All
callers converted to handle a failure.

Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox
2019-04-05 14:02:10 -07:00
committed by Linus Torvalds
parent 8fde12ca79
commit 15fab63e1e
5 changed files with 29 additions and 15 deletions
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4
fs/pipe.c
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@@ -189,9 +189,9 @@ EXPORT_SYMBOL(generic_pipe_buf_steal);
* in the tee() system call, when we duplicate the buffers in one
* pipe into another.
*/
void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
{
get_page(buf->page);
return try_get_page(buf->page);
}
EXPORT_SYMBOL(generic_pipe_buf_get);