Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9d48017b authored by Nickolai Zeldovich's avatar Nickolai Zeldovich Committed by Dave Kleikamp
Browse files

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: default avatarNickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: default avatarDave Kleikamp <dave.kleikamp@oracle.com>
parent 5f243b9b

fs/jfs/jfs_imap.c

+1 −1
Original line number Diff line number Diff line
@@ -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;