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| author | Tom Tromey <tromey@adacore.com> | 2021-07-30 11:18:36 -0600 |
|---|---|---|
| committer | Tom Tromey <tromey@adacore.com> | 2021-08-02 07:46:30 -0600 |
| commit | 4d0754c5f572b01cf2fe6c8ab292adba83331cbc (patch) | |
| tree | 71adad0241d4be3751c09966b5f95dda68137c1c | |
| parent | c894449a790e00cf6fcc079a1efce88437472aaf (diff) | |
| download | gdb-4d0754c5f572b01cf2fe6c8ab292adba83331cbc.zip gdb-4d0754c5f572b01cf2fe6c8ab292adba83331cbc.tar.gz gdb-4d0754c5f572b01cf2fe6c8ab292adba83331cbc.tar.bz2 | |
Avoid crash in varobj deletion
PR varobj/28131 points out a crash in the varobj deletion code. It
took a while to reproduce this, but essentially what happens is that a
top-level varobj deletes its root object, then deletes the "dynamic"
object. However, deletion of the dynamic object may cause
~py_varobj_iter to run, which in turn uses gdbpy_enter_varobj:
gdbpy_enter_varobj::gdbpy_enter_varobj (const struct varobj *var)
: gdbpy_enter (var->root->exp->gdbarch, var->root->exp->language_defn)
{
}
However, because var->root has already been destroyed, this is
invalid.
I've added a new test case. This doesn't reliably crash, but the
problem can easily be seen under valgrind (and, I presume, with ASAN,
though I did not try this).
Tested on x86-64 Fedora 32. I also propose putting this on the GDB 11
branch, with a suitable ChangeLog entry of course.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28131
| -rw-r--r-- | gdb/testsuite/gdb.python/py-mi-var-info-path-expression.exp | 12 | ||||
| -rw-r--r-- | gdb/varobj.c | 6 |
2 files changed, 16 insertions, 2 deletions
diff --git a/gdb/testsuite/gdb.python/py-mi-var-info-path-expression.exp b/gdb/testsuite/gdb.python/py-mi-var-info-path-expression.exp index 2688851..4328c59 100644 --- a/gdb/testsuite/gdb.python/py-mi-var-info-path-expression.exp +++ b/gdb/testsuite/gdb.python/py-mi-var-info-path-expression.exp @@ -85,3 +85,15 @@ mi_gdb_test "-var-list-children c1.car.atom" \ mi_gdb_test "-var-info-path-expression c1.car.atom.ival" \ "\\^error,msg=\".*\"" \ "-var-info-path-expression c1.car.atom.ival" + + +# Regression test for a crasher that would occur when deleting a +# varobj that held an iterator that hadn't yet been completed. +# See PR varobj/28131. +mi_gdb_test "-var-create c1_again * &c1" \ + "\\^done.*" \ + "-var-create c1_again * &c1" +mi_gdb_test "-var-list-children c1_again 0 1" \ + "\\^done,numchild=\"1\",children=.child=\{name=\"c1_again.car\".*" \ + "-var-list-children c1_again" +mi_delete_varobj c1_again "delete c1_again" diff --git a/gdb/varobj.c b/gdb/varobj.c index 7928d90..d0c857a 100644 --- a/gdb/varobj.c +++ b/gdb/varobj.c @@ -1844,10 +1844,12 @@ varobj::~varobj () } #endif + /* This must be deleted before the root object, because Python-based + destructors need access to some components. */ + delete var->dynamic; + if (is_root_p (var)) delete var->root; - - delete var->dynamic; } /* Return the type of the value that's stored in VAR, |