| Summary: | Crash with set logging redirect and debugredirect | ||
|---|---|---|---|
| Product: | gdb | Reporter: | Nate Eldredge <nate> |
| Component: | gdb | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | lsix, nate, tromey |
| Priority: | P2 | ||
| Version: | HEAD | ||
| Target Milestone: | 11.1 | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | ||
| Attachments: | Patch to fix the issue | ||
|
Description
Nate Eldredge
2020-12-31 07:08:27 UTC
Created attachment 13118 [details]
Patch to fix the issue
Hi,
This comes dowm to a use after delete problem.
The attach patch has been proposed to gdb-patches@.
I cannot assign myself to the bug so I mainly attach this patch so no-one spends time investigating on this problem.
Multiple implementations are possible to solve this problem, none entirely satisfactory to my taste.
The master branch has been updated by Lancelot SIX <lsix@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=59b59f08f6448a77730c8d8dde5871f1bf6806d0 commit 59b59f08f6448a77730c8d8dde5871f1bf6806d0 Author: Lancelot SIX <lsix@lancelotsix.com> Date: Fri Jan 1 20:11:28 2021 +0000 Avoid use after free with logging and debug redirect. This patch addresses PR gdb/27133. Before it, the following succession of commands would cause gdb to crash: set logging redirect on set logging debugredirect on set logging on The problem eventually comes down to a use after free. The function cli_interp_base::set_logging is called with a unique_ptr argument that holds a pointer to the redirection file. In the problematic use case, no-one ever took ownership of that pointer (as far as unique_ptr is concerned), so the call to its dtor at the end of the function causes the file object to be deleted. Any later use of the pointer to the redirection file is therefore an error. This patch ensures that the unique_ptr is released when required (so it does not assume ownership anymore). The internal logic of cli_interp_base::set_logging takes care of freeing the ui_file when it is not necessary anymore using the saved_output.file_to_delete field. gdb/ChangeLog: PR gdb/27133 * cli/cli-interp.c (cli_interp_base::set_logging): Ensure the unique_ptr is released when the wrapped pointer is kept for later use. gdb/testsuite/ChangeLog: PR gdb/27133 * gdb.base/ui-redirect.exp: Add test case that ensures that redirecting both logging and debug does not cause gdb to crash. Fixed. |