From 9d48017bce890b19e3bba649850bdbc8a6f95903 Mon Sep 17 00:00:00 2001 From: Nickolai Zeldovich Date: Sat, 5 Jan 2013 14:19:21 -0500 Subject: jfs: avoid undefined behavior from left-shifting by 32 bits Shifting a 32-bit int by 32 bits is undefined behavior in C, and results in different behavior on different architectures (e.g., x86 and PowerPC). diAlloc() in fs/jfs/jfs_imap.c computes a mask using 0xffffffffu<<(32-bitno), which can left-shift by 32 bits. To avoid unexpected behavior, explicitly check for bitno==0 and use a 0 mask. Signed-off-by: Nickolai Zeldovich Signed-off-by: Dave Kleikamp --- fs/jfs/jfs_imap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/jfs/jfs_imap.c') diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c index 6ba4006e011b..f7e042b63ddb 100644 --- a/fs/jfs/jfs_imap.c +++ b/fs/jfs/jfs_imap.c @@ -1493,7 +1493,7 @@ int diAlloc(struct inode *pip, bool dir, struct inode *ip) /* mask any prior bits for the starting words of the * summary map. */ - mask = ONES << (EXTSPERSUM - bitno); + mask = (bitno == 0) ? 0 : (ONES << (EXTSPERSUM - bitno)); inosmap = le32_to_cpu(iagp->inosmap[sword]) | mask; extsmap = le32_to_cpu(iagp->extsmap[sword]) | mask; -- cgit v1.2.3