backport work-around for UBSAN-errors with variable arrays

Link: openzfs/zfs#15510
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

debian/patches/0013-Workaround-UBSAN-errors-for-variable-arrays.patch

@@ -0,0 +1,75 @@
+From 28be24aefc13b11e4c96e172cf2685994e03150d Mon Sep 17 00:00:00 2001
+From: Tony Hutter <hutter2@llnl.gov>
+Date: Thu, 9 Nov 2023 16:43:35 -0800
+Subject: [PATCH] Workaround UBSAN errors for variable arrays
+
+This gets around UBSAN errors when using arrays at the end of
+structs.  It converts some zero-length arrays to variable length
+arrays and disables UBSAN checking on certain modules.
+
+It is based off of the patch from #15460.
+
+Addresses: #15145
+Signed-off-by: Tony Hutter <hutter2@llnl.gov>
+Co-authored-by: Tony Hutter <hutter2@llnl.gov>
+Co-authored-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
+Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
+---
+ include/os/linux/spl/sys/kmem_cache.h | 2 +-
+ include/sys/vdev_raidz_impl.h         | 4 ++--
+ module/Kbuild.in                      | 4 ++++
+ 3 files changed, 7 insertions(+), 3 deletions(-)
+
+diff --git a/include/os/linux/spl/sys/kmem_cache.h b/include/os/linux/spl/sys/kmem_cache.h
+index 20eeadc46..82d50b603 100644
+--- a/include/os/linux/spl/sys/kmem_cache.h
++++ b/include/os/linux/spl/sys/kmem_cache.h
+@@ -108,7 +108,7 @@ typedef struct spl_kmem_magazine {
+ 	uint32_t		skm_refill;	/* Batch refill size */
+ 	struct spl_kmem_cache	*skm_cache;	/* Owned by cache */
+ 	unsigned int		skm_cpu;	/* Owned by cpu */
+-	void			*skm_objs[0];	/* Object pointers */
++	void			*skm_objs[];	/* Object pointers */
+ } spl_kmem_magazine_t;
+
+ typedef struct spl_kmem_obj {
+diff --git a/include/sys/vdev_raidz_impl.h b/include/sys/vdev_raidz_impl.h
+index c1037fa12..73c26dff1 100644
+--- a/include/sys/vdev_raidz_impl.h
++++ b/include/sys/vdev_raidz_impl.h
+@@ -130,7 +130,7 @@ typedef struct raidz_row {
+ 	uint64_t rr_offset;		/* Logical offset for *_io_verify() */
+ 	uint64_t rr_size;		/* Physical size for *_io_verify() */
+ #endif
+-	raidz_col_t rr_col[0];		/* Flexible array of I/O columns */
++	raidz_col_t rr_col[];		/* Flexible array of I/O columns */
+ } raidz_row_t;
+
+ typedef struct raidz_map {
+@@ -139,7 +139,7 @@ typedef struct raidz_map {
+ 	int rm_nskip;			/* RAIDZ sectors skipped for padding */
+ 	int rm_skipstart;		/* Column index of padding start */
+ 	const raidz_impl_ops_t *rm_ops;	/* RAIDZ math operations */
+-	raidz_row_t *rm_row[0];		/* flexible array of rows */
++	raidz_row_t *rm_row[];		/* flexible array of rows */
+ } raidz_map_t;
+
+
+diff --git a/module/Kbuild.in b/module/Kbuild.in
+index c13217159..b9c284a24 100644
+--- a/module/Kbuild.in
++++ b/module/Kbuild.in
+@@ -488,6 +488,10 @@ zfs-$(CONFIG_ARM64) += $(addprefix zfs/,$(ZFS_OBJS_ARM64))
+ zfs-$(CONFIG_PPC)   += $(addprefix zfs/,$(ZFS_OBJS_PPC_PPC64))
+ zfs-$(CONFIG_PPC64) += $(addprefix zfs/,$(ZFS_OBJS_PPC_PPC64))
+
++UBSAN_SANITIZE_zap_leaf.o := n
++UBSAN_SANITIZE_zap_micro.o := n
++UBSAN_SANITIZE_sa.o := n
++
+ # Suppress incorrect warnings from versions of objtool which are not
+ # aware of x86 EVEX prefix instructions used for AVX512.
+ OBJECT_FILES_NON_STANDARD_vdev_raidz_math_avx512bw.o := y
+-- 
+2.39.2
+

debian/patches/series

@@ -10,3 +10,4 @@
 0010-zvol-Remove-broken-blk-mq-optimization.patch
 0011-Revert-zvol-Temporally-disable-blk-mq.patch
 0012-Fix-nfs_truncate_shares-without-etc-exports.d.patch
+0013-Workaround-UBSAN-errors-for-variable-arrays.patch