linux-kernel - [PATCH v3 06/11] kgdb: Prevent infinite recursive entries to the debugger

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Message-Id: <20200428141218.v3.6.I89de39f68736c9de610e6f241e68d8dbc44bc266@changeid>
Date:   Tue, 28 Apr 2020 14:13:46 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     jason.wessel@...driver.com, daniel.thompson@...aro.org,
        gregkh@...uxfoundation.org
Cc:     agross@...nel.org, kgdb-bugreport@...ts.sourceforge.net,
        catalin.marinas@....com, linux-serial@...r.kernel.org,
        sumit.garg@...aro.org, corbet@....net, mingo@...hat.com,
        will@...nel.org, hpa@...or.com, tglx@...utronix.de,
        frowand.list@...il.com, bp@...en8.de, bjorn.andersson@...aro.org,
        jslaby@...e.com, Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 06/11] kgdb: Prevent infinite recursive entries to the debugger

If we detect that we recursively entered the debugger we should hack
our I/O ops to NULL so that the panic() in the next line won't
actually cause another recursion into the debugger.  The first line of
kgdb_panic() will check this and return.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

Changes in v3:
- ("kgdb: Prevent infinite recursive entries to the debugger") new for v3.

Changes in v2: None

 kernel/debug/debug_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 503c1630ca76..faf5bd4c34ee 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -532,6 +532,7 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
 
 	if (exception_level > 1) {
 		dump_stack();
+		kgdb_io_module_registered = false;
 		panic("Recursive entry to debugger");
 	}
 
-- 
2.26.2.303.gf8c07b1a785-goog