https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77535
Bug ID: 77535
Summary: GNAT.Perfect_Hash_Generators access invalid memory
with non-1-based strings
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
Assignee: unassigned at gcc dot gnu.org
Reporter: fw at gcc dot gnu.org
Target Milestone: ---
Created attachment 39585
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39585&action=edit
phg2.adb
Natasha Kerensikova reported this to comp.lang.ada. The attached file was
downloaded from:
http://users.instinctive.eu/nat/phg/
When running it under valgrind, I get:
==4196== Invalid read of size 1
==4196== at 0x5032D23: ??? (in /usr/lib/x86_64-linux-gnu/libgnat-4.9.so.1)
==4196== by 0x5035254: gnat__perfect_hash_generators__compute (in
/usr/lib/x86_64-linux-gnu/libgnat-4.9.so.1)
==4196== by 0x402F3B: _ada_phg2 (in /tmp/g/phg2)
==4196== by 0x402DA5: main (in /tmp/g/phg2)
==4196== Address 0x5e61837 is 23 bytes after a block of size 16 alloc'd
==4196== at 0x4C28C20: malloc (vg_replace_malloc.c:296)
==4196== by 0x507F403: __gnat_malloc (in
/usr/lib/x86_64-linux-gnu/libgnat-4.9.so.1)
==4196== by 0x5033413: ??? (in /usr/lib/x86_64-linux-gnu/libgnat-4.9.so.1)
==4196== by 0x5035098: gnat__perfect_hash_generators__compute (in
/usr/lib/x86_64-linux-gnu/libgnat-4.9.so.1)
==4196== by 0x402F3B: _ada_phg2 (in /tmp/g/phg2)
==4196== by 0x402DA5: main (in /tmp/g/phg2)
Others have reported a segfault.
This is apparently due to GNAT.Perfect_Hash_Generators not dealing properly
with non-1-based strings.
