From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753233AbdBCX1m (ORCPT ); Fri, 3 Feb 2017 18:27:42 -0500 Received: from mail-pg0-f42.google.com ([74.125.83.42]:36612 "EHLO mail-pg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753132AbdBCX1F (ORCPT ); Fri, 3 Feb 2017 18:27:05 -0500 From: Kees Cook To: Peter Zijlstra Cc: Kees Cook , elena.reshetova@intel.com, gregkh@linuxfoundation.org, arnd@arndb.de, tglx@linutronix.de, mingo@kernel.org, h.peter.anvin@intel.com, will.deacon@arm.com, dwindsor@gmail.com, Hans Liljestrand , dhowells@redhat.com, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [PATCH 4/4] refcount: Report failures through CHECK_DATA_CORRUPTION Date: Fri, 3 Feb 2017 15:26:52 -0800 Message-Id: <1486164412-7338-5-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1486164412-7338-1-git-send-email-keescook@chromium.org> References: <1486164412-7338-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This converts from WARN_ON() to CHECK_DATA_CORRUPTION() in the CONFIG_DEBUG_REFCOUNT case. Additionally moves refcount_t sanity check conditionals into regular function flow. Since CHECK_DATA_CORRUPTION() is marked __much_check, we override few cases where the failure has already been handled but we want to explicitly report it. Signed-off-by: Kees Cook --- include/linux/refcount.h | 35 ++++++++++++++++++++++------------- lib/Kconfig.debug | 2 ++ 2 files changed, 24 insertions(+), 13 deletions(-) diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 5b89cad62237..ef32910c7dd8 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -43,10 +43,10 @@ #include #if CONFIG_DEBUG_REFCOUNT -#define REFCOUNT_WARN(cond, str) WARN_ON(cond) +#define REFCOUNT_CHECK(cond, str) CHECK_DATA_CORRUPTION(cond, str) #define __refcount_check __must_check #else -#define REFCOUNT_WARN(cond, str) (void)(cond) +#define REFCOUNT_CHECK(cond, str) (!!(cond)) #define __refcount_check #endif @@ -86,14 +86,18 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r) break; } - REFCOUNT_WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); + val = REFCOUNT_CHECK(new == UINT_MAX, + "refcount_t: add saturated; leaking memory.\n"); return true; } static inline void refcount_add(unsigned int i, refcount_t *r) { - REFCOUNT_WARN(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n"); + bool __always_unused b; + + b = REFCOUNT_CHECK(!refcount_add_not_zero(i, r), + "refcount_t: addition on 0; use-after-free.\n"); } /* @@ -121,7 +125,8 @@ bool refcount_inc_not_zero(refcount_t *r) break; } - REFCOUNT_WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); + val = REFCOUNT_CHECK(new == UINT_MAX, + "refcount_t: inc saturated; leaking memory.\n"); return true; } @@ -134,7 +139,10 @@ bool refcount_inc_not_zero(refcount_t *r) */ static inline void refcount_inc(refcount_t *r) { - REFCOUNT_WARN(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n"); + bool __always_unused b; + + b = REFCOUNT_CHECK(!refcount_inc_not_zero(r), + "refcount_t: increment on 0; use-after-free.\n"); } /* @@ -155,10 +163,9 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r) return false; new = val - i; - if (new > val) { - REFCOUNT_WARN(new > val, "refcount_t: underflow; use-after-free.\n"); + if (REFCOUNT_CHECK(new > val, + "refcount_t: sub underflow; use-after-free.\n")) return false; - } if (atomic_try_cmpxchg_release(&r->refs, &val, new)) break; @@ -183,7 +190,10 @@ bool refcount_dec_and_test(refcount_t *r) static inline void refcount_dec(refcount_t *r) { - REFCOUNT_WARN(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n"); + bool __always_unused b; + + b = REFCOUNT_CHECK(refcount_dec_and_test(r), + "refcount_t: decrement hit 0; leaking memory.\n"); } /* @@ -224,10 +234,9 @@ bool refcount_dec_not_one(refcount_t *r) return false; new = val - 1; - if (new > val) { - REFCOUNT_WARN(new > val, "refcount_t: underflow; use-after-free.\n"); + if (REFCOUNT_CHECK(new > val, + "refcount_t: dec underflow; use-after-free.\n")) return true; - } if (atomic_try_cmpxchg_release(&r->refs, &val, new)) break; diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 20fde8d4523a..01e7aa578456 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -731,6 +731,7 @@ source "lib/Kconfig.kasan" config DEBUG_REFCOUNT bool "Verbose refcount checks" + depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION help Say Y here if you want reference counters (refcount_t and kref) to generate WARNs on dubious usage. Without this refcount_t will still @@ -2011,6 +2012,7 @@ config TEST_STATIC_KEYS config BUG_ON_DATA_CORRUPTION bool "Trigger a BUG when data corruption is detected" select DEBUG_LIST + select DEBUG_REFCOUNT help Select this option if the kernel should BUG when it encounters data corruption in kernel memory structures when they get checked -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Date: Fri, 3 Feb 2017 15:26:52 -0800 Message-Id: <1486164412-7338-5-git-send-email-keescook@chromium.org> In-Reply-To: <1486164412-7338-1-git-send-email-keescook@chromium.org> References: <1486164412-7338-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH 4/4] refcount: Report failures through CHECK_DATA_CORRUPTION To: Peter Zijlstra Cc: Kees Cook , elena.reshetova@intel.com, gregkh@linuxfoundation.org, arnd@arndb.de, tglx@linutronix.de, mingo@kernel.org, h.peter.anvin@intel.com, will.deacon@arm.com, dwindsor@gmail.com, Hans Liljestrand , dhowells@redhat.com, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com List-ID: This converts from WARN_ON() to CHECK_DATA_CORRUPTION() in the CONFIG_DEBUG_REFCOUNT case. Additionally moves refcount_t sanity check conditionals into regular function flow. Since CHECK_DATA_CORRUPTION() is marked __much_check, we override few cases where the failure has already been handled but we want to explicitly report it. Signed-off-by: Kees Cook --- include/linux/refcount.h | 35 ++++++++++++++++++++++------------- lib/Kconfig.debug | 2 ++ 2 files changed, 24 insertions(+), 13 deletions(-) diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 5b89cad62237..ef32910c7dd8 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -43,10 +43,10 @@ #include #if CONFIG_DEBUG_REFCOUNT -#define REFCOUNT_WARN(cond, str) WARN_ON(cond) +#define REFCOUNT_CHECK(cond, str) CHECK_DATA_CORRUPTION(cond, str) #define __refcount_check __must_check #else -#define REFCOUNT_WARN(cond, str) (void)(cond) +#define REFCOUNT_CHECK(cond, str) (!!(cond)) #define __refcount_check #endif @@ -86,14 +86,18 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r) break; } - REFCOUNT_WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); + val = REFCOUNT_CHECK(new == UINT_MAX, + "refcount_t: add saturated; leaking memory.\n"); return true; } static inline void refcount_add(unsigned int i, refcount_t *r) { - REFCOUNT_WARN(!refcount_add_not_zero(i, r), "refcount_t: addition on 0; use-after-free.\n"); + bool __always_unused b; + + b = REFCOUNT_CHECK(!refcount_add_not_zero(i, r), + "refcount_t: addition on 0; use-after-free.\n"); } /* @@ -121,7 +125,8 @@ bool refcount_inc_not_zero(refcount_t *r) break; } - REFCOUNT_WARN(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); + val = REFCOUNT_CHECK(new == UINT_MAX, + "refcount_t: inc saturated; leaking memory.\n"); return true; } @@ -134,7 +139,10 @@ bool refcount_inc_not_zero(refcount_t *r) */ static inline void refcount_inc(refcount_t *r) { - REFCOUNT_WARN(!refcount_inc_not_zero(r), "refcount_t: increment on 0; use-after-free.\n"); + bool __always_unused b; + + b = REFCOUNT_CHECK(!refcount_inc_not_zero(r), + "refcount_t: increment on 0; use-after-free.\n"); } /* @@ -155,10 +163,9 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r) return false; new = val - i; - if (new > val) { - REFCOUNT_WARN(new > val, "refcount_t: underflow; use-after-free.\n"); + if (REFCOUNT_CHECK(new > val, + "refcount_t: sub underflow; use-after-free.\n")) return false; - } if (atomic_try_cmpxchg_release(&r->refs, &val, new)) break; @@ -183,7 +190,10 @@ bool refcount_dec_and_test(refcount_t *r) static inline void refcount_dec(refcount_t *r) { - REFCOUNT_WARN(refcount_dec_and_test(r), "refcount_t: decrement hit 0; leaking memory.\n"); + bool __always_unused b; + + b = REFCOUNT_CHECK(refcount_dec_and_test(r), + "refcount_t: decrement hit 0; leaking memory.\n"); } /* @@ -224,10 +234,9 @@ bool refcount_dec_not_one(refcount_t *r) return false; new = val - 1; - if (new > val) { - REFCOUNT_WARN(new > val, "refcount_t: underflow; use-after-free.\n"); + if (REFCOUNT_CHECK(new > val, + "refcount_t: dec underflow; use-after-free.\n")) return true; - } if (atomic_try_cmpxchg_release(&r->refs, &val, new)) break; diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 20fde8d4523a..01e7aa578456 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -731,6 +731,7 @@ source "lib/Kconfig.kasan" config DEBUG_REFCOUNT bool "Verbose refcount checks" + depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION help Say Y here if you want reference counters (refcount_t and kref) to generate WARNs on dubious usage. Without this refcount_t will still @@ -2011,6 +2012,7 @@ config TEST_STATIC_KEYS config BUG_ON_DATA_CORRUPTION bool "Trigger a BUG when data corruption is detected" select DEBUG_LIST + select DEBUG_REFCOUNT help Select this option if the kernel should BUG when it encounters data corruption in kernel memory structures when they get checked -- 2.7.4