| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 128/130] signalfd: fix information leak in signalfd_copyinfo | Date | Fri, 4 Sep 2015 14:08:36 +0100 |
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3.16.7-ckt17 -stable review patch. If anyone has any objections, please let me know.
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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: Luis Henriques <luis.henriques@canonical.com> --- fs/signalfd.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/signalfd.c b/fs/signalfd.c index 424b7b65321f..148f8e7af882 100644 --- a/fs/signalfd.c +++ b/fs/signalfd.c @@ -121,8 +121,9 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo, * 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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