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authorLinus Torvalds <torvalds@linux-foundation.org>2019-05-06 11:39:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-06 11:39:17 -0700
commit6ec62961e6de9506e8b8620dc19897d8cfd41c2e (patch)
tree8da8868e763b1fa1f5633acd549bc7e32eb0527e /lib/ubsan.c
parent171c2bcbcb58a6699dad64d0c0b615af4f6ecb74 (diff)
parent29da93fea3ea39ab9b12270cc6be1b70ef201c9e (diff)
Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar: "This is a series from Peter Zijlstra that adds x86 build-time uaccess validation of SMAP to objtool, which will detect and warn about the following uaccess API usage bugs and weirdnesses: - call to %s() with UACCESS enabled - return with UACCESS enabled - return with UACCESS disabled from a UACCESS-safe function - recursive UACCESS enable - redundant UACCESS disable - UACCESS-safe disables UACCESS As it turns out not leaking uaccess permissions outside the intended uaccess functionality is hard when the interfaces are complex and when such bugs are mostly dormant. As a bonus we now also check the DF flag. We had at least one high-profile bug in that area in the early days of Linux, and the checking is fairly simple. The checks performed and warnings emitted are: - call to %s() with DF set - return with DF set - return with modified stack frame - recursive STD - redundant CLD It's all x86-only for now, but later on this can also be used for PAN on ARM and objtool is fairly cross-platform in principle. While all warnings emitted by this new checking facility that got reported to us were fixed, there might be GCC version dependent warnings that were not reported yet - which we'll address, should they trigger. The warnings are non-fatal build warnings" * 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation sched/x86_64: Don't save flags on context switch objtool: Add Direction Flag validation objtool: Add UACCESS validation objtool: Fix sibling call detection objtool: Rewrite alt->skip_orig objtool: Add --backtrace support objtool: Rewrite add_ignores() objtool: Handle function aliases objtool: Set insn->func for alternatives x86/uaccess, kcov: Disable stack protector x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP x86/uaccess, ubsan: Fix UBSAN vs. SMAP x86/uaccess, kasan: Fix KASAN vs SMAP x86/smap: Ditch __stringify() x86/uaccess: Introduce user_access_{save,restore}() x86/uaccess, signal: Fix AC=1 bloat x86/uaccess: Always inline user_access_begin() x86/uaccess, xen: Suppress SMAP warnings ...
Diffstat (limited to 'lib/ubsan.c')
-rw-r--r--lib/ubsan.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/lib/ubsan.c b/lib/ubsan.c
index c4859c2d2f1b..ecc179338094 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -17,6 +17,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
+#include <linux/uaccess.h>
#include "ubsan.h"
@@ -311,6 +312,7 @@ static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
unsigned long ptr)
{
+ unsigned long flags = user_access_save();
if (!ptr)
handle_null_ptr_deref(data);
@@ -318,6 +320,8 @@ static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
handle_misaligned_access(data, ptr);
else
handle_object_size_mismatch(data, ptr);
+
+ user_access_restore(flags);
}
void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,