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authorBill O'Donnell <billodo@redhat.com>2019-10-04 16:38:44 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-10-06 15:39:06 -0700
commit3219e8cf0dade9884d3c6cb432d433b4ca56875d (patch)
treeac636fd31c84fd346ec0c923783aafb71033a4c3 /fs/xfs
parentd5cc14d9f92833bd71219bf7fff180f097c3816d (diff)
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: 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>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_buf.c12
-rw-r--r--fs/xfs/xfs_log.c2
-rw-r--r--fs/xfs/xfs_log_recover.c2
3 files changed, 13 insertions, 3 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 21c243622a79..0abba171aa89 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -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;
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index a2beee9f74da..641d07f30a27 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -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
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 508319039dce..c1a514ffff55 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -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);
}
/*