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| author | Daniel Thompson <daniel.thompson@linaro.org> | 2020-09-27 22:15:29 +0100 |
|---|---|---|
| committer | Daniel Thompson <daniel.thompson@linaro.org> | 2020-09-28 12:14:08 +0100 |
| commit | f2d10ff4a903813df767a4b56b651a26b938df06 (patch) | |
| tree | a6969351434aa9c2eac82e8bec42115a01df2507 /kernel/debug | |
| parent | e16c33e290792c9b71b952dc915e5f7dfc9d4409 (diff) | |
| download | linux-f2d10ff4a903813df767a4b56b651a26b938df06.tar.gz linux-f2d10ff4a903813df767a4b56b651a26b938df06.tar.bz2 linux-f2d10ff4a903813df767a4b56b651a26b938df06.zip | |
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')
| -rw-r--r-- | kernel/debug/debug_core.c | 4 | ||||
| -rw-r--r-- | kernel/debug/kdb/kdb_bp.c | 9 |
2 files changed, 13 insertions, 0 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 165e5b0c2083..6b9383fa8278 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -180,6 +180,10 @@ int __weak kgdb_validate_break_address(unsigned long addr) { struct kgdb_bkpt tmp; int err; + + if (kgdb_within_blocklist(addr)) + return -EINVAL; + /* Validate setting the breakpoint and then removing it. If the * remove fails, the kernel needs to emit a bad message because we * are deep trouble not being able to put things back the way we 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++) { |