Commit 3219e8cf authored by Bill O'Donnell's avatar Bill O'Donnell Committed by Darrick J. Wong
Browse files

xfs: assure zeroed memory buffers for certain kmem allocations 



Guarantee zeroed memory buffers for cases where potential memory
leak to disk can occur. In these cases, kmem_alloc is used and
doesn't zero the buffer, opening the possibility of information
leakage to disk.

Use existing infrastucture (xfs_buf_allocate_memory) to obtain
the already zeroed buffer from kernel memory.

This solution avoids the performance issue that would occur if a
wholesale change to replace kmem_alloc with kmem_zalloc was done.

Signed-off-by: default avatarBill O'Donnell <billodo@redhat.com>
[darrick: fix bitwise complaint about kmflag_mask]
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent d5cc14d9

fs/xfs/xfs_buf.c

+11 −1
Original line number Diff line number Diff line
@@ -345,6 +345,15 @@ xfs_buf_allocate_memory( 
	unsigned short		page_count, i;

	xfs_off_t		start, end;

	int			error;

	xfs_km_flags_t		kmflag_mask = 0;



	/*

	 * assure zeroed buffer for non-read cases.

	 */

	if (!(flags & XBF_READ)) {

		kmflag_mask |= KM_ZERO;

		gfp_mask |= __GFP_ZERO;

	}



	/*

	 * for buffers that are contained within a single page, just allocate
@@ -354,7 +363,8 @@ xfs_buf_allocate_memory( 
	size = BBTOB(bp->b_length);

	if (size < PAGE_SIZE) {

		int align_mask = xfs_buftarg_dma_alignment(bp->b_target);

		bp->b_addr = kmem_alloc_io(size, align_mask, KM_NOFS);

		bp->b_addr = kmem_alloc_io(size, align_mask,

					   KM_NOFS | kmflag_mask);

		if (!bp->b_addr) {

			/* low memory - use alloc_page loop instead */

			goto use_alloc_page;

fs/xfs/xfs_log.c

+1 −1
Original line number Diff line number Diff line
@@ -1443,7 +1443,7 @@ xlog_alloc_log( 
		prev_iclog = iclog;



		iclog->ic_data = kmem_alloc_io(log->l_iclog_size, align_mask,

						KM_MAYFAIL);

						KM_MAYFAIL | KM_ZERO);

		if (!iclog->ic_data)

			goto out_free_iclog;

#ifdef DEBUG

fs/xfs/xfs_log_recover.c

+1 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ xlog_alloc_buffer( 
	if (nbblks > 1 && log->l_sectBBsize > 1)

		nbblks += log->l_sectBBsize;

	nbblks = round_up(nbblks, log->l_sectBBsize);

	return kmem_alloc_io(BBTOB(nbblks), align_mask, KM_MAYFAIL);

	return kmem_alloc_io(BBTOB(nbblks), align_mask, KM_MAYFAIL | KM_ZERO);

}



/*

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