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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 /kernel/debug/kdb/kdb_bp.c
parente16c33e290792c9b71b952dc915e5f7dfc9d4409 (diff)
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 'kernel/debug/kdb/kdb_bp.c')
-rw-r--r--kernel/debug/kdb/kdb_bp.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c
index d7ebb2c79cb8..ec4940146612 100644
--- a/kernel/debug/kdb/kdb_bp.c
+++ b/kernel/debug/kdb/kdb_bp.c
@@ -307,6 +307,15 @@ static int kdb_bp(int argc, const char **argv)
return KDB_BADINT;
/*
+ * This check is redundant (since the breakpoint machinery should
+ * be doing the same check during kdb_bp_install) but gives the
+ * user immediate feedback.
+ */
+ diag = kgdb_validate_break_address(template.bp_addr);
+ if (diag)
+ return diag;
+
+ /*
* Find an empty bp structure to allocate
*/
for (bpno = 0, bp = kdb_breakpoints; bpno < KDB_MAXBPT; bpno++, bp++) {

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