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xfs: fix memcpy fortify errors in BUI log format copying

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Starting in 6.1, CONFIG_FORTIFY_SOURCE checks the length parameter of
memcpy.  Unfortunately, it doesn't handle flex arrays correctly:

------------[ cut here ]------------
memcpy: detected field-spanning write (size 48) of single field "dst_bui_fmt" at fs/xfs/xfs_bmap_item.c:628 (size 16)

Fix this by refactoring the xfs_bui_copy_format function to handle the
copying of the head and the flex array members separately.  While we're
at it, fix a minor validation deficiency in the recovery function.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Darrick J. Wong 2022-10-20 16:17:41 -07:00
parent 59da7ff49d
commit a38ebce1da
2 changed files with 27 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
fs/xfs/xfs_bmap_item.c
View File

@ -608,28 +608,18 @@ static const struct xfs_item_ops xfs_bui_item_ops = {
.iop_relog = xfs_bui_item_relog,
};
/*
* Copy an BUI format buffer from the given buf, and into the destination
* BUI format structure. The BUI/BUD items were designed not to need any
* special alignment handling.
*/
static int
static inline void
xfs_bui_copy_format(
struct xfs_log_iovec *buf,
struct xfs_bui_log_format *dst_bui_fmt)
struct xfs_bui_log_format *dst,
const struct xfs_bui_log_format *src)
{
struct xfs_bui_log_format *src_bui_fmt;
uint len;
unsigned int i;
src_bui_fmt = buf->i_addr;
len = xfs_bui_log_format_sizeof(src_bui_fmt->bui_nextents);
memcpy(dst, src, offsetof(struct xfs_bui_log_format, bui_extents));
if (buf->i_len == len) {
memcpy(dst_bui_fmt, src_bui_fmt, len);
return 0;
}
XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, NULL);
return -EFSCORRUPTED;
for (i = 0; i < src->bui_nextents; i++)
memcpy(&dst->bui_extents[i], &src->bui_extents[i],
sizeof(struct xfs_map_extent));
}
/*
@ -646,23 +636,31 @@ xlog_recover_bui_commit_pass2(
struct xlog_recover_item *item,
xfs_lsn_t lsn)
{
int error;
struct xfs_mount *mp = log->l_mp;
struct xfs_bui_log_item *buip;
struct xfs_bui_log_format *bui_formatp;
size_t len;
bui_formatp = item->ri_buf[0].i_addr;
if (item->ri_buf[0].i_len < xfs_bui_log_format_sizeof(0)) {
XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
return -EFSCORRUPTED;
}
if (bui_formatp->bui_nextents != XFS_BUI_MAX_FAST_EXTENTS) {
XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
return -EFSCORRUPTED;
}
buip = xfs_bui_init(mp);
error = xfs_bui_copy_format(&item->ri_buf[0], &buip->bui_format);
if (error) {
xfs_bui_item_free(buip);
return error;
len = xfs_bui_log_format_sizeof(bui_formatp->bui_nextents);
if (item->ri_buf[0].i_len != len) {
XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
return -EFSCORRUPTED;
}
buip = xfs_bui_init(mp);
xfs_bui_copy_format(&buip->bui_format, bui_formatp);
atomic_set(&buip->bui_next_extent, bui_formatp->bui_nextents);
/*
* Insert the intent into the AIL directly and drop one reference so

5
fs/xfs/xfs_ondisk.h
View File

@ -134,6 +134,11 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_STRUCT_SIZE(struct xfs_trans_header, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_attri_log_format, 40);
XFS_CHECK_STRUCT_SIZE(struct xfs_attrd_log_format, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_bui_log_format, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_bud_log_format, 16);
XFS_CHECK_STRUCT_SIZE(struct xfs_map_extent, 32);
XFS_CHECK_OFFSET(struct xfs_bui_log_format, bui_extents, 16);
/*
* The v5 superblock format extended several v4 header structures with