All of lore.kernel.org
 help / color / mirror / Atom feed
From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Will Deacon <will@kernel.org>, Kees Cook <keescook@chromium.org>,
	Ingo Molnar <mingo@kernel.org>,
	Elena Reshetova <elena.reshetova@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Hanjun Guo <guohanjun@huawei.com>
Subject: [RESEND PATCH v4 02/10] lib/refcount: Ensure integer operands are treated as signed
Date: Thu, 21 Nov 2019 11:58:54 +0000	[thread overview]
Message-ID: <20191121115902.2551-3-will@kernel.org> (raw)
In-Reply-To: <20191121115902.2551-1-will@kernel.org>

In preparation for changing the saturation point of REFCOUNT_FULL to
INT_MIN / 2, change the type of integer operands passed into the API
from 'unsigned int' to 'int' so that we can avoid casting during
comparisons when we don't want to fall foul of C integral conversion
rules for signed and unsigned types.

Since the kernel is compiled with '-fno-strict-overflow', we don't need
to worry about the UB introduced by signed overflow here. Furthermore,
we're already making heavy use of the atomic_t API, which operates
exclusively on signed types.

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
 include/linux/refcount.h | 14 +++++++-------
 lib/refcount.c           |  6 +++---
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/linux/refcount.h b/include/linux/refcount.h
index 79f62e8d2256..89066a1471dd 100644
--- a/include/linux/refcount.h
+++ b/include/linux/refcount.h
@@ -28,7 +28,7 @@ typedef struct refcount_struct {
  * @r: the refcount
  * @n: value to which the refcount will be set
  */
-static inline void refcount_set(refcount_t *r, unsigned int n)
+static inline void refcount_set(refcount_t *r, int n)
 {
 	atomic_set(&r->refs, n);
 }
@@ -44,13 +44,13 @@ static inline unsigned int refcount_read(const refcount_t *r)
 	return atomic_read(&r->refs);
 }
 
-extern __must_check bool refcount_add_not_zero_checked(unsigned int i, refcount_t *r);
-extern void refcount_add_checked(unsigned int i, refcount_t *r);
+extern __must_check bool refcount_add_not_zero_checked(int i, refcount_t *r);
+extern void refcount_add_checked(int i, refcount_t *r);
 
 extern __must_check bool refcount_inc_not_zero_checked(refcount_t *r);
 extern void refcount_inc_checked(refcount_t *r);
 
-extern __must_check bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r);
+extern __must_check bool refcount_sub_and_test_checked(int i, refcount_t *r);
 
 extern __must_check bool refcount_dec_and_test_checked(refcount_t *r);
 extern void refcount_dec_checked(refcount_t *r);
@@ -79,12 +79,12 @@ extern void refcount_dec_checked(refcount_t *r);
 # ifdef CONFIG_ARCH_HAS_REFCOUNT
 #  include <asm/refcount.h>
 # else
-static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r)
+static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r)
 {
 	return atomic_add_unless(&r->refs, i, 0);
 }
 
-static inline void refcount_add(unsigned int i, refcount_t *r)
+static inline void refcount_add(int i, refcount_t *r)
 {
 	atomic_add(i, &r->refs);
 }
@@ -99,7 +99,7 @@ static inline void refcount_inc(refcount_t *r)
 	atomic_inc(&r->refs);
 }
 
-static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r)
+static inline __must_check bool refcount_sub_and_test(int i, refcount_t *r)
 {
 	return atomic_sub_and_test(i, &r->refs);
 }
diff --git a/lib/refcount.c b/lib/refcount.c
index 48b78a423d7d..719b0bc42ab1 100644
--- a/lib/refcount.c
+++ b/lib/refcount.c
@@ -61,7 +61,7 @@
  *
  * Return: false if the passed refcount is 0, true otherwise
  */
-bool refcount_add_not_zero_checked(unsigned int i, refcount_t *r)
+bool refcount_add_not_zero_checked(int i, refcount_t *r)
 {
 	unsigned int new, val = atomic_read(&r->refs);
 
@@ -101,7 +101,7 @@ EXPORT_SYMBOL(refcount_add_not_zero_checked);
  * cases, refcount_inc(), or one of its variants, should instead be used to
  * increment a reference count.
  */
-void refcount_add_checked(unsigned int i, refcount_t *r)
+void refcount_add_checked(int i, refcount_t *r)
 {
 	WARN_ONCE(!refcount_add_not_zero_checked(i, r), "refcount_t: addition on 0; use-after-free.\n");
 }
@@ -180,7 +180,7 @@ EXPORT_SYMBOL(refcount_inc_checked);
  *
  * Return: true if the resulting refcount is 0, false otherwise
  */
-bool refcount_sub_and_test_checked(unsigned int i, refcount_t *r)
+bool refcount_sub_and_test_checked(int i, refcount_t *r)
 {
 	unsigned int new, val = atomic_read(&r->refs);
 
-- 
2.24.0.432.g9d3f5f5b63-goog


  parent reply	other threads:[~2019-11-21 11:59 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-21 11:58 [RESEND PATCH v4 00/10] Rework REFCOUNT_FULL using atomic_fetch_* operations Will Deacon
2019-11-21 11:58 ` [RESEND PATCH v4 01/10] lib/refcount: Define constants for saturation and max refcount values Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2019-11-21 11:58 ` Will Deacon [this message]
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: Ensure integer operands are treated as signed tip-bot2 for Will Deacon
2019-11-21 11:58 ` [RESEND PATCH v4 03/10] lib/refcount: Remove unused refcount_*_checked() variants Will Deacon
2019-11-21 14:55   ` David Sterba
2019-11-21 17:11     ` Kees Cook
2019-11-21 17:17       ` David Sterba
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2019-11-21 11:58 ` [RESEND PATCH v4 04/10] lib/refcount: Move bulk of REFCOUNT_FULL implementation into header Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header tip-bot2 for Will Deacon
2019-11-21 11:58 ` [RESEND PATCH v4 05/10] lib/refcount: Improve performance of generic REFCOUNT_FULL code Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2020-02-26  4:10   ` [RESEND PATCH v4 05/10] lib/refcount: " Jann Horn
2020-02-26  4:10     ` Jann Horn
2020-02-28 10:43     ` Will Deacon
2020-03-02 13:06       ` Jann Horn
2020-03-02 13:06         ` Jann Horn
2019-11-21 11:58 ` [RESEND PATCH v4 06/10] lib/refcount: Move saturation warnings out of line Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2019-11-21 11:58 ` [RESEND PATCH v4 07/10] lib/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2019-11-21 11:59 ` [RESEND PATCH v4 08/10] refcount: Consolidate implementations of refcount_t Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2019-12-01 15:49   ` [refcount] d2d337b185: WARNING:at_lib/refcount.c:#refcount_warn_saturate kernel test robot
2019-12-01 15:49     ` kernel test robot
2019-12-02  9:43     ` Ard Biesheuvel
2019-12-02  9:43       ` Ard Biesheuvel
2019-12-03  8:01       ` [LKP] " Rong Chen
2019-12-03  8:01         ` Rong Chen
2019-12-03  8:09         ` [LKP] " Will Deacon
2019-12-03  8:09           ` Will Deacon
2019-12-03  8:42           ` [LKP] " Rong Chen
2019-12-03  8:42             ` Rong Chen
2019-11-21 11:59 ` [RESEND PATCH v4 09/10] lib/refcount: Remove unused 'refcount_error_report()' function Will Deacon
2019-11-25  8:19   ` [tip: locking/core] locking/refcount: " tip-bot2 for Will Deacon
2019-11-21 11:59 ` [RESEND PATCH v4 10/10] drivers/lkdtm: Remove references to CONFIG_REFCOUNT_FULL Will Deacon
2019-11-25  8:19   ` [tip: locking/core] lkdtm: " tip-bot2 for Will Deacon
2019-11-21 12:07 ` [RESEND PATCH v4 00/10] Rework REFCOUNT_FULL using atomic_fetch_* operations Ard Biesheuvel
2019-11-22  3:44 ` Hanjun Guo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191121115902.2551-3-will@kernel.org \
    --to=will@kernel.org \
    --cc=ard.biesheuvel@linaro.org \
    --cc=elena.reshetova@intel.com \
    --cc=guohanjun@huawei.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.