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To: Trond Myklebust <trond.myklebust@hammerspace.com>, Anna Schumaker
	<anna@kernel.org>, <linux-nfs@vger.kernel.org>
From: Sergey Shtylyov <s.shtylyov@omp.ru>
Subject: [PATCH] nfs: fix undefined behavior in nfs_block_bits()
Organization: Open Mobile Platform
Message-ID: <69333a8c-a5a7-5c76-bc39-8835f11b8dcf@omp.ru>
Date: Fri, 10 May 2024 23:24:04 +0300
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Shifting *signed int* typed constant 1 left by 31 bits causes undefined
behavior. Specify the correct *unsigned long* type by using 1UL instead.

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Cc: stable@vger.kernel.org
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

---
This patch is against the master branch of Trond Myklebust's linux-nfs.git repo.

fs/nfs/internal.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-nfs/fs/nfs/internal.h
===================================================================
--- linux-nfs.orig/fs/nfs/internal.h
+++ linux-nfs/fs/nfs/internal.h
@@ -710,9 +710,9 @@ unsigned long nfs_block_bits(unsigned lo
 	if ((bsize & (bsize - 1)) || nrbitsp) {
 		unsigned char	nrbits;
 
-		for (nrbits = 31; nrbits && !(bsize & (1 << nrbits)); nrbits--)
+		for (nrbits = 31; nrbits && !(bsize & (1UL << nrbits)); nrbits--)
 			;
-		bsize = 1 << nrbits;
+		bsize = 1UL << nrbits;
 		if (nrbitsp)
 			*nrbitsp = nrbits;
 	}