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authorEric Sandeen <sandeen@redhat.com>2015-10-12 16:04:15 +1100
committerDave Chinner <david@fromorbit.com>2015-10-12 16:04:15 +1100
commit91f9f5fe1e7350e872b3fbc3194e8183bddce514 (patch)
tree5aa10aef830c70180c090d43d4cf905baf5d2f54 /fs/xfs/xfs_log.c
parentdbd5c8c9a28899c6ca719eb21afc0afba9dd5574 (diff)
xfs: avoid null *src in memcpy call in xlog_write
The gcc undefined behavior sanitizer caught this; surely any sane memcpy implementation will no-op if size == 0, but behavior with a *src of NULL is technically undefined (declared nonnull), so avoid it here. We are actually in this situation frequently via xlog_commit_record(), because: struct xfs_log_iovec reg = { .i_addr = NULL, .i_len = 0, .i_type = XLOG_REG_TYPE_COMMIT, }; Reported-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_log.c')
-rw-r--r--fs/xfs/xfs_log.c17
1 files changed, 13 insertions, 4 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 0c8ef767c3a9..af08326b0e41 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2422,11 +2422,20 @@ xlog_write(
&partial_copy_len);
xlog_verify_dest_ptr(log, ptr);
- /* copy region */
+ /*
+ * Copy region.
+ *
+ * Unmount records just log an opheader, so can have
+ * empty payloads with no data region to copy. Hence we
+ * only copy the payload if the vector says it has data
+ * to copy.
+ */
ASSERT(copy_len >= 0);
- memcpy(ptr, reg->i_addr + copy_off, copy_len);
- xlog_write_adv_cnt(&ptr, &len, &log_offset, copy_len);
-
+ if (copy_len > 0) {
+ memcpy(ptr, reg->i_addr + copy_off, copy_len);
+ xlog_write_adv_cnt(&ptr, &len, &log_offset,
+ copy_len);
+ }
copy_len += start_rec_copy + sizeof(xlog_op_header_t);
record_cnt++;
data_cnt += contwr ? copy_len : 0;