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SubjectRe: [PATCH 3.14 30/44] signalfd: fix information leak in signalfd_copyinfo
On Fri, Aug 14, 2015 at 10:45:07AM -0700, Greg Kroah-Hartman wrote:
> 3.14-stable review patch. If anyone has any objections, please let me know.
>

These 3 patches seem to be relevant to other stable trees as well. I'm
queuing them for the 3.16 kernel.

Cheers,
--
Luís


> ------------------
>
> From: Amanieu d'Antras <amanieu@gmail.com>
>
> commit 3ead7c52bdb0ab44f4bb1feed505a8323cc12ba7 upstream.
>
> This function may copy the si_addr_lsb field to user mode when it hasn't
> been initialized, which can leak kernel stack data to user mode.
>
> Just checking the value of si_code is insufficient because the same
> si_code value is shared between multiple signals. This is solved by
> checking the value of si_signo in addition to si_code.
>
> Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> fs/signalfd.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -121,8 +121,9 @@ static int signalfd_copyinfo(struct sign
> * Other callers might not initialize the si_lsb field,
> * so check explicitly for the right codes here.
> */
> - if (kinfo->si_code == BUS_MCEERR_AR ||
> - kinfo->si_code == BUS_MCEERR_AO)
> + if (kinfo->si_signo == SIGBUS &&
> + (kinfo->si_code == BUS_MCEERR_AR ||
> + kinfo->si_code == BUS_MCEERR_AO))
> err |= __put_user((short) kinfo->si_addr_lsb,
> &uinfo->ssi_addr_lsb);
> #endif
>
>
> --
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