Add `--enable-asan` and `--enable-ubsan` switches

`configure` now accepts `--enable-asan` and `--enable-ubsan` switches
which results in passing `-fsanitize=address`
and `-fsanitize=undefined`, respectively, to the compiler. Those
flags are enabled in GitHub workflows for ZTS and zloop. Errors
reported by both instrumentations are corrected, except for:

- Memory leak reporting is (temporarily) suppressed. The cost of
  fixing them is relatively high compared to the gains.

- Checksum computing functions in `module/zcommon/zfs_fletcher*`
  have UBSan errors suppressed. It is completely impractical
  to enforce 64-byte payload alignment there due to performance
  impact.

- There's no ASan heap poisoning in `module/zstd/lib/zstd.c`. A custom
  memory allocator is used there rendering that measure
  unfeasible.

- Memory leaks detection has to be suppressed for `cmd/zvol_id`.
  `zvol_id` is run by udev with the help of `ptrace(2)`. Tracing is
  incompatible with memory leaks detection.

Reviewed-by: Ahelenia Ziemiańska <[email protected]>
Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: szubersk <[email protected]>
Closes #12928 

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/libzfs/libzfs_mount.c b/lib/libzfs/libzfs_mount.c
index 0932cb1de..62c46be95 100644
--- a/lib/libzfs/libzfs_mount.c
+++ b/lib/libzfs/libzfs_mount.c
@@ -1611,7 +1611,8 @@ zpool_disable_datasets(zpool_handle_t *zhp, boolean_t force)
 	 * At this point, we have the entire list of filesystems, so sort it by
 	 * mountpoint.
 	 */
-	qsort(sets, used, sizeof (struct sets_s), mountpoint_compare);
+	if (used != 0)
+		qsort(sets, used, sizeof (struct sets_s), mountpoint_compare);
 
 	/*
 	 * Walk through and first unshare everything.