Commit cb512c92 authored by Dave Chinner's avatar Dave Chinner Committed by Dave Chinner
Browse files

xfs: zero inode fork buffer at allocation 



When we first allocate or resize an inline inode fork, we round up
the allocation to 4 byte alingment to make journal alignment
constraints. We don't clear the unused bytes, so we can copy up to
three uninitialised bytes into the journal. Zero those bytes so we
only ever copy zeros into the journal.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarAllison Henderson <allison.henderson@oracle.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent a44a027a

fs/xfs/libxfs/xfs_inode_fork.c

+9 −3
Original line number Diff line number Diff line
@@ -50,8 +50,13 @@ xfs_init_local_fork( 
		mem_size++;



	if (size) {

		/*

		 * As we round up the allocation here, we need to ensure the

		 * bytes we don't copy data into are zeroed because the log

		 * vectors still copy them into the journal.

		 */

		real_size = roundup(mem_size, 4);

		ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS);

		ifp->if_u1.if_data = kmem_zalloc(real_size, KM_NOFS);

		memcpy(ifp->if_u1.if_data, data, size);

		if (zero_terminate)

			ifp->if_u1.if_data[size] = '\0';
@@ -500,10 +505,11 @@ xfs_idata_realloc( 
	/*

	 * For inline data, the underlying buffer must be a multiple of 4 bytes

	 * in size so that it can be logged and stay on word boundaries.

	 * We enforce that here.

	 * We enforce that here, and use __GFP_ZERO to ensure that size

	 * extensions always zero the unused roundup area.

	 */

	ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, roundup(new_size, 4),

				      GFP_NOFS | __GFP_NOFAIL);

				      GFP_NOFS | __GFP_NOFAIL | __GFP_ZERO);

	ifp->if_bytes = new_size;

}