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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2013-09-11 21:23:18 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 22:58:18 (GMT)
commit3ddc5b46a8e90f3c9251338b60191d0a804b0d92 (patch)
tree5c76cd730cb94e75f30953d6cd1aed9386fcee37 /arch
parent20d0e57017b69e7e4ae7166c43f3a3f023ab9702 (diff)
downloadlinux-3ddc5b46a8e90f3c9251338b60191d0a804b0d92.tar.xz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/alpha/lib/csum_partial_copy.c5
-rw-r--r--arch/sparc/kernel/sys_sparc32.c12
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;
}