Without the patch, do_mt_entry() can call dump_struct_members_for_tree() with a NULL entry, and parse_for_member_extended() will cause a segmentation fault during strncpy(). This is caused by "tree -t maple -s struct.member.member" style multiple level member access: crash> tree -t maple -s irq_desc.irq_data.irq sparse_irqs ffff936980188400 irq_data.irq = 0, ffff93698018be00 irq_data.irq = 1, ... ffff936980f38e00 irq_data.irq = 19, Segmentation fault (core dumped) (gdb) bt #0 0x00007faaf8e51635 in __strncpy_avx2 () from /lib64/libc.so.6 #1 0x00000000005e5927 in parse_for_member_extended (dm=dm@entry=0x7ffcb9e6d860, ... #2 0x0000000000603c45 in dump_struct_member (s=s@entry=0x128cde0 <shared_bufs+1024> ... #3 0x0000000000513cf5 in dump_struct_members_for_tree (td=td@entry=0x7ffcb9e6eeb0, ... #4 0x0000000000651f15 in do_mt_entry (entry=0, min=min@entry=20, max=max@entry=119, ... ... Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; --- maple_tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/maple_tree.c b/maple_tree.c index eccd273105a6..8c804d0cb80d 100644 --- a/maple_tree.c +++ b/maple_tree.c @@ -313,7 +313,7 @@ static void do_mt_entry(ulong entry, ulong min, ulong max, uint depth, fprintf(fp, " index: %ld position: %s/%u\n", ++(*global_index), path, index); - if (td->structname) { + if (td->structname && entry) { if (td->flags & TREE_STRUCT_RADIX_10) print_radix = 10; else if (td->flags & TREE_STRUCT_RADIX_16) -- 2.31.1