xfs: zero inode fork buffer at allocation

[ Upstream commit cb512c921639613ce03f87e62c5e93ed9fe8c84d ]

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: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 1d174909f9bdf5deffeb5caa9f565ef1b9b9fab5..20095233d7bc04e3eca910e99e00055374cc0dbf 100644 (file)
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -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;
 }