From 3ddc5b46a8e90f3c9251338b60191d0a804b0d92 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Wed, 11 Sep 2013 14:23:18 -0700 Subject: kernel-wide: fix missing validations on __get/__put/__copy_to/__copy_from_user() I found the following pattern that leads in to interesting findings: grep -r "ret.*|=.*__put_user" * grep -r "ret.*|=.*__get_user" * grep -r "ret.*|=.*__copy" * The __put_user() calls in compat_ioctl.c, ptrace compat, signal compat, since those appear in compat code, we could probably expect the kernel addresses not to be reachable in the lower 32-bit range, so I think they might not be exploitable. For the "__get_user" cases, I don't think those are exploitable: the worse that can happen is that the kernel will copy kernel memory into in-kernel buffers, and will fail immediately afterward. The alpha csum_partial_copy_from_user() seems to be missing the access_ok() check entirely. The fix is inspired from x86. This could lead to information leak on alpha. I also noticed that many architectures map csum_partial_copy_from_user() to csum_partial_copy_generic(), but I wonder if the latter is performing the access checks on every architectures. Signed-off-by: Mathieu Desnoyers Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Jens Axboe Cc: Oleg Nesterov Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/signal.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/signal.c b/kernel/signal.c index 50e41075ac77..ded28b91fa53 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3394,7 +3394,7 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, new_ka.sa.sa_restorer = compat_ptr(restorer); #endif ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask)); - ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags); + ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); if (ret) return -EFAULT; sigset_from_compat(&new_ka.sa.sa_mask, &mask); @@ -3406,7 +3406,7 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), &oact->sa_handler); ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask)); - ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags); + ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); #ifdef __ARCH_HAS_SA_RESTORER ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer); -- cgit v1.2.3