From: Nickolai Zeldovich Date: Sat, 5 Jan 2013 19:19:21 +0000 (-0500) Subject: jfs: avoid undefined behavior from left-shifting by 32 bits X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9d48017bce890b19e3bba649850bdbc8a6f95903;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git 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 --- 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;