Re: [Qemu-devel] [PATCH 17/29] 9pfs: local: readlink: don't follow symlinks

[Stefan Hajnoczi]

On Mon, Feb 20, 2017 at 03:41:32PM +0100, Greg Kurz wrote:
> The local_readlink() callback is vulnerable to symlink attacks because it
> calls:
> 
> (1) open(O_NOFOLLOW) which follows symbolic links for all path elements but
>     the rightmost one
> (2) readlink() which follows symbolic links for all path elements but the
>     rightmost one
> 
> This patch converts local_readlink() to rely on open_nofollow() to fix (1)
> and opendir_nofollow(), readlinkat() to fix (2).
> 
> This partly fixes CVE-2016-9602.
> 
> Signed-off-by: Greg Kurz <address@hidden>
> ---
>  hw/9pfs/9p-local.c |   26 +++++++++++++++++---------
>  1 file changed, 17 insertions(+), 9 deletions(-)

Reviewed-by: Stefan Hajnoczi <address@hidden>

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