fs: prevent page refcount overflow in pipe_buf_get
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>
diff --git a/fs/splice.c b/fs/splice.c
index de2ede0..f30af82 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1588,7 +1588,11 @@ static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
* Get a reference to this pipe buffer,
* so we can copy the contents over.
*/
- pipe_buf_get(ipipe, ibuf);
+ if (!pipe_buf_get(ipipe, ibuf)) {
+ if (ret == 0)
+ ret = -EFAULT;
+ break;
+ }
*obuf = *ibuf;
/*
@@ -1660,7 +1664,11 @@ static int link_pipe(struct pipe_inode_info *ipipe,
* Get a reference to this pipe buffer,
* so we can copy the contents over.
*/
- pipe_buf_get(ipipe, ibuf);
+ if (!pipe_buf_get(ipipe, ibuf)) {
+ if (ret == 0)
+ ret = -EFAULT;
+ break;
+ }
obuf = opipe->bufs + nbuf;
*obuf = *ibuf;