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xfs: zero inode fork buffer at allocation

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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>
This commit is contained in:
Dave Chinner 2022-05-04 11:44:55 +10:00 committed by Dave Chinner
parent a44a027a8b
commit cb512c9216
1 changed files with 9 additions and 3 deletions
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12
fs/xfs/libxfs/xfs_inode_fork.c
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@ -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;
}