6.16-stable review patch. If anyone has any objections, please let me know.
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From: SeongJae Park sj@kernel.org
commit 964314344eab7bc43e38a32be281c5ea0609773b upstream.
If 'enable' parameter of the 'mtier' DAMON sample module is set at boot time via the kernel command line, memory allocation is tried before the slab is initialized. As a result kernel NULL pointer dereference BUG can happen. Fix it by checking the initialization status.
Link: https://lkml.kernel.org/r/20250706193207.39810-4-sj@kernel.org Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering") Signed-off-by: SeongJae Park sj@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- samples/damon/mtier.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/samples/damon/mtier.c +++ b/samples/damon/mtier.c @@ -151,6 +151,8 @@ static void damon_sample_mtier_stop(void damon_destroy_ctx(ctxs[1]); }
+static bool init_called; + static int damon_sample_mtier_enable_store( const char *val, const struct kernel_param *kp) { @@ -176,6 +178,14 @@ static int damon_sample_mtier_enable_sto
static int __init damon_sample_mtier_init(void) { + int err = 0; + + init_called = true; + if (enable) { + err = damon_sample_mtier_start(); + if (err) + enable = false; + } return 0; }