| From 26135022f85105ad725cda103fa069e29e83bd16 Mon Sep 17 00:00:00 2001 |
| From: Amanieu d'Antras <amanieu@gmail.com> |
| Date: Thu, 6 Aug 2015 15:46:29 -0700 |
| Subject: signal: fix information leak in copy_siginfo_to_user |
| |
| From: Amanieu d'Antras <amanieu@gmail.com> |
| |
| 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 <amanieu@gmail.com> |
| Cc: Oleg Nesterov <oleg@redhat.com> |
| Cc: Ingo Molnar <mingo@kernel.org> |
| Cc: Russell King <rmk@arm.linux.org.uk> |
| 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> |
| |
| --- |
| arch/arm64/kernel/signal32.c | 3 ++- |
| kernel/signal.c | 3 ++- |
| 2 files changed, 4 insertions(+), 2 deletions(-) |
| |
| --- a/arch/arm64/kernel/signal32.c |
| +++ b/arch/arm64/kernel/signal32.c |
| @@ -193,7 +193,8 @@ int copy_siginfo_to_user32(compat_siginf |
| * 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; |
| --- a/kernel/signal.c |
| +++ b/kernel/signal.c |
| @@ -2768,7 +2768,8 @@ int copy_siginfo_to_user(siginfo_t __use |
| * 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; |