[PATCH 1/1] gdb: fix assert after register write failure

[Eduard Sargsyan <eduard.sargsyan@intel.com>]

GDB tries to invalidate register cache if write to register fails.  In case
when write was requested to be done for a remote inferior and connection with
remote is dead (so write request will fail) GDB cleans register caches and as
result setting register status fails with segmentation fault, because internal
pointers are not valid anymore and the unique_ptr with register status is
null.

This change adds check if register status cache is still valid before trying to
modify (set status to UNKNOWN).

gdb/ChangeLog:
2021-03-18  Eduard Sargsyan  <eduard.sargsyan@intel.com>

	* regcache.c (regcache::raw_write): Add check for pointer validity.
---
 gdb/regcache.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gdb/regcache.c b/gdb/regcache.c
index 6140a05f02b..94ca89a58de 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -882,8 +882,11 @@ regcache::raw_write (int regnum, gdb::array_view<const gdb_byte> src)
 
   /* Invalidate the register after it is written, in case of a
      failure.  */
-  auto invalidator
-    = make_scope_exit ([&] { this->invalidate (regnum); });
+  auto invalidator = make_scope_exit ([&]
+    {
+      if (this->m_register_status != nullptr)
+	this->invalidate (regnum);
+    });
 
   target_store_registers (this, regnum);
 
-- 
2.34.1

Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de <http://www.intel.de>
Managing Directors: Christin Eisenschmid, Sharon Heck, Tiffany Doon Silva  
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928