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 <mathieu.desnoyers@efficios.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 11 insertions, 6 deletions

diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c
index 40736da..ffb19b7 100644
--- a/arch/alpha/lib/csum_partial_copy.c
+++ b/arch/alpha/lib/csum_partial_copy.c
@@ -338,6 +338,11 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 	unsigned long doff = 7 & (unsigned long) dst;
 
 	if (len) {
+		if (!access_ok(VERIFY_READ, src, len)) {
+			*errp = -EFAULT;
+			memset(dst, 0, len);
+			return sum;
+		}
 		if (!doff) {
 			if (!soff)
 				checksum = csum_partial_cfu_aligned(
diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c
index 3d0ddbc..7136885 100644
--- a/arch/sparc/kernel/sys_sparc32.c
+++ b/arch/sparc/kernel/sys_sparc32.c
@@ -169,10 +169,10 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig,
 		new_ka.ka_restorer = restorer;
 		ret = get_user(u_handler, &act->sa_handler);
 		new_ka.sa.sa_handler =  compat_ptr(u_handler);
-		ret |= __copy_from_user(&set32, &act->sa_mask, sizeof(compat_sigset_t));
+		ret |= copy_from_user(&set32, &act->sa_mask, sizeof(compat_sigset_t));
 		sigset_from_compat(&new_ka.sa.sa_mask, &set32);
-		ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
-		ret |= __get_user(u_restorer, &act->sa_restorer);
+		ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags);
+		ret |= get_user(u_restorer, &act->sa_restorer);
 		new_ka.sa.sa_restorer = compat_ptr(u_restorer);
                 if (ret)
                 	return -EFAULT;
@@ -183,9 +183,9 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig,
 	if (!ret && oact) {
 		sigset_to_compat(&set32, &old_ka.sa.sa_mask);
 		ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), &oact->sa_handler);
-		ret |= __copy_to_user(&oact->sa_mask, &set32, sizeof(compat_sigset_t));
-		ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
-		ret |= __put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer);
+		ret |= copy_to_user(&oact->sa_mask, &set32, sizeof(compat_sigset_t));
+		ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags);
+		ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer);
 		if (ret)
 			ret = -EFAULT;
         }