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From: Arnd Bergmann <arnd@kernel.org>
To: linux-kernel@vger.kernel.org, Nathan Chancellor <nathan@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Dmitry Vyukov <dvyukov@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	kasan-dev@googlegroups.com, llvm@lists.linux.dev
Subject: [PATCH 4/9] kcov: avoid clang out-of-range warning
Date: Thu, 28 Mar 2024 15:30:42 +0100	[thread overview]
Message-ID: <20240328143051.1069575-5-arnd@kernel.org> (raw)
In-Reply-To: <20240328143051.1069575-1-arnd@kernel.org>

From: Arnd Bergmann <arnd@arndb.de>

The area_size is never larger than the maximum on 64-bit architectutes:

kernel/kcov.c:634:29: error: result of comparison of constant 1152921504606846975 with expression of type '__u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
                if (remote_arg->area_size > LONG_MAX / sizeof(unsigned long))
                    ~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The compiler can correctly optimize the check away and the code appears
correct to me, so just add a cast to avoid the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/kcov.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/kcov.c b/kernel/kcov.c
index f9ac2e9e460f..c3124f6d5536 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -627,7 +627,8 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
 		mode = kcov_get_mode(remote_arg->trace_mode);
 		if (mode < 0)
 			return mode;
-		if (remote_arg->area_size > LONG_MAX / sizeof(unsigned long))
+		if ((unsigned long)remote_arg->area_size >
+		    LONG_MAX / sizeof(unsigned long))
 			return -EINVAL;
 		kcov->mode = mode;
 		t->kcov = kcov;
-- 
2.39.2


  parent reply	other threads:[~2024-03-28 14:31 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-28 14:30 [PATCH 0/9] address remaining -Wtautological-constant-out-of-range-compare Arnd Bergmann
2024-03-28 14:30 ` [PATCH 1/9] dm integrity: fix out-of-range warning Arnd Bergmann
2024-03-28 18:36   ` Mikulas Patocka
2024-03-28 21:58   ` Justin Stitt
2024-03-28 14:30 ` [PATCH 2/9] libceph: avoid clang " Arnd Bergmann
2024-03-28 22:53   ` Justin Stitt
2024-03-29  0:06   ` Xiubo Li
2024-03-28 14:30 ` [PATCH 3/9] rbd: avoid " Arnd Bergmann
2024-03-28 14:53   ` Alex Elder
2024-03-29  0:05     ` Xiubo Li
2024-03-28 14:30 ` Arnd Bergmann [this message]
2024-03-28 22:22   ` [PATCH 4/9] kcov: avoid clang " Justin Stitt
2024-03-28 14:30 ` [PATCH 5/9] ipv4: tcp_output: avoid warning about NET_ADD_STATS Arnd Bergmann
2024-03-28 14:38   ` Eric Dumazet
2024-03-28 16:39     ` Arnd Bergmann
2024-03-28 14:30 ` [PATCH 6/9] nilfs2: fix out-of-range warning Arnd Bergmann
2024-03-28 15:21   ` Philipp Stanner
2024-03-28 16:12     ` Arnd Bergmann
2024-03-28 22:04   ` Justin Stitt
2024-03-28 22:25     ` Arnd Bergmann
2024-03-29  9:20   ` Ryusuke Konishi
2024-04-01  8:50   ` (subset) " Christian Brauner
2024-03-28 14:30 ` [PATCH 7/9] infiniband: uverbs: avoid out-of-range warnings Arnd Bergmann
2024-03-28 22:12   ` Justin Stitt
2024-04-03 15:45   ` Jason Gunthorpe
2024-04-03 20:16     ` Arnd Bergmann
2024-03-28 14:30 ` [PATCH 8/9] mlx5: stop warning for 64KB pages Arnd Bergmann
2024-03-28 15:37   ` Maxim Mikityanskiy
2024-03-28 22:09   ` Justin Stitt
2024-03-28 22:21     ` Arnd Bergmann
2024-03-28 22:39   ` Tariq Toukan
2024-03-28 14:30 ` [PATCH 9/9] kbuild: enable tautological-constant-out-of-range-compare Arnd Bergmann
2024-03-29 20:00 ` [PATCH 0/9] address remaining -Wtautological-constant-out-of-range-compare patchwork-bot+netdevbpf

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