linux-kernel - [PATCH 2/9] libceph: avoid clang out-of-range warning

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Date: Thu, 28 Mar 2024 15:30:40 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: linux-kernel@...r.kernel.org,
	Xiubo Li <xiubli@...hat.com>,
	Ilya Dryomov <idryomov@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Nathan Chancellor <nathan@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>,
	Jeff Layton <jlayton@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Milind Changire <mchangir@...hat.com>,
	Patrick Donnelly <pdonnell@...hat.com>,
	Christian Brauner <brauner@...nel.org>,
	ceph-devel@...r.kernel.org,
	netdev@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH 2/9] libceph: avoid clang out-of-range warning

From: Arnd Bergmann <arnd@...db.de>

clang-14 points out that on 64-bit architectures, a u32
is never larger than constant based on SIZE_MAX:

net/ceph/osdmap.c:1425:10: error: result of comparison of constant 4611686018427387891 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
        if (len > (SIZE_MAX - sizeof(*pg)) / sizeof(u32))
            ~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/ceph/osdmap.c:1608:10: error: result of comparison of constant 2305843009213693945 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
        if (len > (SIZE_MAX - sizeof(*pg)) / (2 * sizeof(u32)))
            ~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The code is correct anyway, so just shut up that warning.

Fixes: 6f428df47dae ("libceph: pg_upmap[_items] infrastructure")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/ceph/snap.c    | 2 +-
 net/ceph/osdmap.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index c65f2b202b2b..521507ea8260 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -374,7 +374,7 @@ static int build_snap_context(struct ceph_mds_client *mdsc,
 
 	/* alloc new snap context */
 	err = -ENOMEM;
-	if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
+	if ((size_t)num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
 		goto fail;
 	snapc = ceph_create_snap_context(num, GFP_NOFS);
 	if (!snapc)
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 295098873861..8e7cb2fde6f1 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -1438,7 +1438,7 @@ static struct ceph_pg_mapping *__decode_pg_temp(void **p, void *end,
 	ceph_decode_32_safe(p, end, len, e_inval);
 	if (len == 0 && incremental)
 		return NULL;	/* new_pg_temp: [] to remove */
-	if (len > (SIZE_MAX - sizeof(*pg)) / sizeof(u32))
+	if ((size_t)len > (SIZE_MAX - sizeof(*pg)) / sizeof(u32))
 		return ERR_PTR(-EINVAL);
 
 	ceph_decode_need(p, end, len * sizeof(u32), e_inval);
@@ -1621,7 +1621,7 @@ static struct ceph_pg_mapping *__decode_pg_upmap_items(void **p, void *end,
 	u32 len, i;
 
 	ceph_decode_32_safe(p, end, len, e_inval);
-	if (len > (SIZE_MAX - sizeof(*pg)) / (2 * sizeof(u32)))
+	if ((size_t)len > (SIZE_MAX - sizeof(*pg)) / (2 * sizeof(u32)))
 		return ERR_PTR(-EINVAL);
 
 	ceph_decode_need(p, end, 2 * len * sizeof(u32), e_inval);
-- 
2.39.2