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From: Lancelot SIX <lsix@sourceware.org> To: gdb-cvs@sourceware.org Subject: [binutils-gdb] gdb: Fix regression in varobj recreation Date: Wed, 3 Aug 2022 09:00:34 +0000 (GMT) [thread overview] Message-ID: <20220803090034.937413858CDB@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f74a5e6f2ed5180ce28d6478a6d7a7a1982c5d43 commit f74a5e6f2ed5180ce28d6478a6d7a7a1982c5d43 Author: Lancelot SIX <lancelot.six@amd.com> Date: Tue Aug 2 13:14:20 2022 +0100 gdb: Fix regression in varobj recreation Commit bc20e562ec0 "Fix use after free in varobj" introduced a regression. This commit makes sure that the varobj object does not keeps stale references to object being freed when we unload an objfile. This includes the "valid_block" field which is reset to nullptr if the pointed to block is tied to an objfile being freed. However, at some point varobj_invalidate_iter might try to recreate varobjs tracking either floating or globals. Varobj tracking globals are identified as having the "valid_block" field set nullptr, but as bc20e562ec0 might clear this field, we have lost the ability to distinguish between varobj referring to globals and non globals. Fix this by introducing a "global" flag which tracks if a given varobj was initially created as tracking a global. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29426 Diff: --- gdb/varobj.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/gdb/varobj.c b/gdb/varobj.c index e558794617a..0683af1991e 100644 --- a/gdb/varobj.c +++ b/gdb/varobj.c @@ -102,6 +102,9 @@ struct varobj_root to symbols that do not exist anymore. */ bool is_valid = true; + /* Set to true if the varobj was created as tracking a global. */ + bool global = false; + /* Language-related operations for this variable and its children. */ const struct lang_varobj_ops *lang_ops = NULL; @@ -336,6 +339,8 @@ varobj_create (const char *objname, var->format = variable_default_display (var.get ()); var->root->valid_block = var->root->floating ? NULL : tracker.block (); + var->root->global + = var->root->floating ? false : var->root->valid_block == nullptr; var->name = expression; /* For a root var, the name and the expr are the same. */ var->path_expr = expression; @@ -2359,7 +2364,7 @@ static void varobj_invalidate_iter (struct varobj *var) { /* global and floating var must be re-evaluated. */ - if (var->root->floating || var->root->valid_block == nullptr) + if (var->root->floating || var->root->global) { struct varobj *tmp_var; @@ -2375,7 +2380,7 @@ varobj_invalidate_iter (struct varobj *var) varobj_delete (var, 0); install_variable (tmp_var); } - else if (!var->root->floating) + else if (var->root->global) { /* Only invalidate globals as floating vars might still be valid in some other frame. */
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