6.16-stable review patch. If anyone has any objections, please let me know.
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From: SeongJae Park sj@kernel.org
[ Upstream commit 2780505ec2b42c07853b34640bc63279ac2bb53b ]
If 'enable' parameter of the 'prcl' 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/20250706193207.39810-3-sj@kernel.org Fixes: 2aca254620a8 ("samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation") Signed-off-by: SeongJae Park sj@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Stable-dep-of: c62cff40481c ("samples/damon/mtier: avoid starting DAMON before initialization") Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- samples/damon/prcl.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/samples/damon/prcl.c +++ b/samples/damon/prcl.c @@ -109,6 +109,8 @@ static void damon_sample_prcl_stop(void) put_pid(target_pidp); }
+static bool init_called; + static int damon_sample_prcl_enable_store( const char *val, const struct kernel_param *kp) { @@ -134,6 +136,14 @@ static int damon_sample_prcl_enable_stor
static int __init damon_sample_prcl_init(void) { + int err = 0; + + init_called = true; + if (enable) { + err = damon_sample_prcl_start(); + if (err) + enable = false; + } return 0; }