From 16a49557bc101b804a0a74d4032556f8836b9469 Mon Sep 17 00:00:00 2001 From: Amanieu d'Antras Date: Thu, 6 Aug 2015 15:46:29 -0700 Subject: [PATCH] signal: fix information leak in copy_siginfo_to_user commit 26135022f85105ad725cda103fa069e29e83bd16 upstream. This function may copy the si_addr_lsb, si_lower and si_upper fields to user mode when they haven'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 Cc: Oleg Nesterov Cc: Ingo Molnar Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/signal32.c | 3 ++- kernel/signal.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c index 3d478102b1c0..efd1dde7094b 100644 --- a/arch/arm64/kernel/signal32.c +++ b/arch/arm64/kernel/signal32.c @@ -193,7 +193,8 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from) * Other callers might not initialize the si_lsb field, * so check explicitely for the right codes here. */ - if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO) + if (from->si_signo == SIGBUS && + (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)) err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); #endif break; diff --git a/kernel/signal.c b/kernel/signal.c index 113411bfe8b1..fa80d104cbec 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2768,7 +2768,8 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) * Other callers might not initialize the si_lsb field, * so check explicitly for the right codes here. */ - if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO) + if (from->si_signo == SIGBUS && + (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)) err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); #endif break; -- 2.20.1