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xfs: assure zeroed memory buffers for certain kmem allocations

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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: Bill O'Donnell <billodo@redhat.com>
[darrick: fix bitwise complaint about kmflag_mask]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Bill O'Donnell
2019-10-04 16:38:44 -07:00
committed by Darrick J. Wong
parent d5cc14d9f9
commit 3219e8cf0d
3 changed files with 13 additions and 3 deletions
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2
fs/xfs/xfs_log_recover.c
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@@ -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);
}
/*