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authorDaniel Thompson <daniel.thompson@linaro.org>2020-09-27 22:15:29 +0100
committerDaniel Thompson <daniel.thompson@linaro.org>2020-09-28 12:14:08 +0100
commitf2d10ff4a903813df767a4b56b651a26b938df06 (patch)
treea6969351434aa9c2eac82e8bec42115a01df2507 /lib
parente16c33e290792c9b71b952dc915e5f7dfc9d4409 (diff)
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kgdb: Honour the kprobe blocklist when setting breakpoints
Currently kgdb has absolutely no safety rails in place to discourage or prevent a user from placing a breakpoint in dangerous places such as the debugger's own trap entry/exit and other places where it is not safe to take synchronous traps. Introduce a new config symbol KGDB_HONOUR_BLOCKLIST and modify the default implementation of kgdb_validate_break_address() so that we use the kprobe blocklist to prohibit instrumentation of critical functions if the config symbol is set. The config symbol dependencies are set to ensure that the blocklist will be enabled by default if we enable KGDB and are compiling for an architecture where we HAVE_KPROBES. Suggested-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20200927211531.1380577-2-daniel.thompson@linaro.org Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.kgdb15
1 files changed, 15 insertions, 0 deletions
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
index 256f2486f9bd..05dae05b6cc9 100644
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -24,6 +24,21 @@ menuconfig KGDB
if KGDB
+config KGDB_HONOUR_BLOCKLIST
+ bool "KGDB: use kprobe blocklist to prohibit unsafe breakpoints"
+ depends on HAVE_KPROBES
+ depends on MODULES
+ select KPROBES
+ default y
+ help
+ If set to Y the debug core will use the kprobe blocklist to
+ identify symbols where it is unsafe to set breakpoints.
+ In particular this disallows instrumentation of functions
+ called during debug trap handling and thus makes it very
+ difficult to inadvertently provoke recursive trap handling.
+
+ If unsure, say Y.
+
config KGDB_SERIAL_CONSOLE
tristate "KGDB: use kgdb over the serial console"
select CONSOLE_POLL