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authorKees Cook <keescook@chromium.org>2016-08-17 14:42:11 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-10-31 13:01:58 -0700
commitde54ebbe26bb371a6f1fbc0593372232f04e3107 (patch)
tree41550879530d6752373feb43eba0d53f39a063a2 /lib/list_debug.c
parent0cd340dcb05c4a43742fe156f36737bb2a321bfd (diff)
bug: Provide toggle for BUG on data corruption
The kernel checks for cases of data structure corruption under some CONFIGs (e.g. CONFIG_DEBUG_LIST). When corruption is detected, some systems may want to BUG() immediately instead of letting the system run with known corruption. Usually these kinds of manipulation primitives can be used by security flaws to gain arbitrary memory write control. This provides a new config CONFIG_BUG_ON_DATA_CORRUPTION and a corresponding macro CHECK_DATA_CORRUPTION for handling these situations. Notably, even if not BUGing, the kernel should not continue processing the corrupted structure. This is inspired by similar hardening by Syed Rameez Mustafa in MSM kernels, and in PaX and Grsecurity, which is likely in response to earlier removal of the BUG calls in commit 924d9addb9b1 ("list debugging: use WARN() instead of BUG()"). Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com>
Diffstat (limited to 'lib/list_debug.c')
-rw-r--r--lib/list_debug.c57
1 files changed, 22 insertions, 35 deletions
diff --git a/lib/list_debug.c b/lib/list_debug.c
index 276565fca2a6..7f7bfa55eb6d 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -20,21 +20,16 @@
bool __list_add_valid(struct list_head *new, struct list_head *prev,
struct list_head *next)
{
- if (unlikely(next->prev != prev)) {
- WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
- prev, next->prev, next);
- return false;
- }
- if (unlikely(prev->next != next)) {
- WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
- next, prev->next, prev);
- return false;
- }
- if (unlikely(new == prev || new == next)) {
- WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n",
- new, prev, next);
- return false;
- }
+ CHECK_DATA_CORRUPTION(next->prev != prev,
+ "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
+ prev, next->prev, next);
+ CHECK_DATA_CORRUPTION(prev->next != next,
+ "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
+ next, prev->next, prev);
+ CHECK_DATA_CORRUPTION(new == prev || new == next,
+ "list_add double add: new=%p, prev=%p, next=%p.\n",
+ new, prev, next);
+
return true;
}
EXPORT_SYMBOL(__list_add_valid);
@@ -46,26 +41,18 @@ bool __list_del_entry_valid(struct list_head *entry)
prev = entry->prev;
next = entry->next;
- if (unlikely(next == LIST_POISON1)) {
- WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
- entry, LIST_POISON1);
- return false;
- }
- if (unlikely(prev == LIST_POISON2)) {
- WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
- entry, LIST_POISON2);
- return false;
- }
- if (unlikely(prev->next != entry)) {
- WARN(1, "list_del corruption. prev->next should be %p, but was %p\n",
- entry, prev->next);
- return false;
- }
- if (unlikely(next->prev != entry)) {
- WARN(1, "list_del corruption. next->prev should be %p, but was %p\n",
- entry, next->prev);
- return false;
- }
+ CHECK_DATA_CORRUPTION(next == LIST_POISON1,
+ "list_del corruption, %p->next is LIST_POISON1 (%p)\n",
+ entry, LIST_POISON1);
+ CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
+ "list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
+ entry, LIST_POISON2);
+ CHECK_DATA_CORRUPTION(prev->next != entry,
+ "list_del corruption. prev->next should be %p, but was %p\n",
+ entry, prev->next);
+ CHECK_DATA_CORRUPTION(next->prev != entry,
+ "list_del corruption. next->prev should be %p, but was %p\n",
+ entry, next->prev);
return true;
}