nfs: fix undefined behavior in nfs_block_bits()

commit 3c0a2e0 upstream. 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: [email protected] Signed-off-by: Sergey Shtylyov <[email protected]> Reviewed-by: Benjamin Coddington <[email protected]> Signed-off-by: Trond Myklebust <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
frank-w · Jun 16, 2024 · 74ea538 · 74ea538
1 parent 2062e3f
commit 74ea538
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
@@ -615,9 +615,9 @@ unsigned long nfs_block_bits(unsigned long bsize, unsigned char *nrbitsp)
 	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;
 	}