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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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12
fs/splice.c
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@@ -1588,7 +1588,11 @@ retry:
* 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;