From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Thu, 3 Jul 2025 17:37:41 +0000 (-0400)
Subject: gdb/linux-nat: initialize lwp_info::syscall_state
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b7ff16c68a2c0bacc0416c4b36a44e65888ce72b;p=thirdparty%2Fbinutils-gdb.git

gdb/linux-nat: initialize lwp_info::syscall_state

When running gdb.base/foll-fork-syscall.exp with a GDB built with UBSan,
I get:

    /home/simark/src/binutils-gdb/gdb/linux-nat.c:1906:28: runtime error: load of value 3200171710, which is not a valid value for type 'target_waitkind'
    ERROR: GDB process no longer exists
    GDB process exited with wait status 3026417 exp9 0 1
    UNRESOLVED: gdb.base/foll-fork-syscall.exp: follow-fork-mode=child: detach-on-fork=on: test_catch_syscall: continue to breakpoint after fork

The error happens here:

    #0  __sanitizer::Die () at /usr/src/debug/gcc/gcc/libsanitizer/sanitizer_common/sanitizer_termination.cpp:50
    #1  0x00007ffff600d8dd in __ubsan::__ubsan_handle_load_invalid_value_abort (Data=<optimized out>, Val=<optimized out>) at /usr/src/debug/gcc/gcc/libsanitizer/ubsan/ubsan_handlers.cpp:551
    #2  0x00005555636d37b6 in linux_handle_syscall_trap (lp=0x7cdff1eb1b00, stopping=0) at /home/simark/src/binutils-gdb/gdb/linux-nat.c:1906
    #3  0x00005555636e0991 in linux_nat_filter_event (lwpid=3030627, status=1407) at /home/simark/src/binutils-gdb/gdb/linux-nat.c:3044
    #4  0x00005555636e407f in linux_nat_wait_1 (ptid=..., ourstatus=0x7bfff0d6cf18, target_options=...) at /home/simark/src/binutils-gdb/gdb/linux-nat.c:3381
    #5  0x00005555636e7795 in linux_nat_target::wait (this=0x5555704d35e0 <the_amd64_linux_nat_target>, ptid=..., ourstatus=0x7bfff0d6cf18, target_options=...) at /home/simark/src/binutils-gdb/gdb/linux-nat.c:3607
    #6  0x000055556378fad2 in thread_db_target::wait (this=0x55556af42980 <the_thread_db_target>, ptid=..., ourstatus=0x7bfff0d6cf18, options=...) at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1398
    #7  0x0000555564811327 in target_wait (ptid=..., status=0x7bfff0d6cf18, options=...) at /home/simark/src/binutils-gdb/gdb/target.c:2593

I believe the problem is that lwp_info::syscall_state is never
initialized.  Fix that by initializing it with TARGET_WAITKIND_IGNORE.
This is the value we use elsewhere when resetting this field to mean
"not stopped at a syscall".

Change-Id: I5b76c63d1466d6e63448fced03305fd5ca8294eb
Approved-By: Tom Tromey <tom@tromey.com>
---

diff --git a/gdb/linux-nat.h b/gdb/linux-nat.h
index 21ec309dafb..7cbe9a98789 100644
--- a/gdb/linux-nat.h
+++ b/gdb/linux-nat.h
@@ -279,12 +279,12 @@ struct lwp_info : intrusive_list_node<lwp_info>
      will be recorded here, while 'status == 0' is ambiguous.  */
   struct target_waitstatus waitstatus;
 
-  /* Signal whether we are in a SYSCALL_ENTRY or
-     in a SYSCALL_RETURN event.
-     Values:
-     - TARGET_WAITKIND_SYSCALL_ENTRY
-     - TARGET_WAITKIND_SYSCALL_RETURN */
-  enum target_waitkind syscall_state;
+  /* Signal whether we are in a SYSCALL_ENTRY or SYSCALL_RETURN event.
+
+     Valid values are TARGET_WAITKIND_SYSCALL_ENTRY,
+     TARGET_WAITKIND_SYSCALL_RETURN, or TARGET_WAITKIND_SYSCALL_IGNORE, when
+     not stopped at a syscall.  */
+  target_waitkind syscall_state = TARGET_WAITKIND_IGNORE;
 
   /* The processor core this LWP was last seen on.  */
   int core = -1;