diff options
| author | Ben Horgan <ben.horgan@arm.com> | 2026-03-06 18:27:16 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2026-03-13 14:17:30 +0000 |
| commit | 4ad79c874e53ebb7fe3b8ae7ac6c858a2121f415 (patch) | |
| tree | f5461fbaa9281117ff0ff7f5f91f3bcf2854fd86 /drivers | |
| parent | d499e9627d70b1269020d59b95ed3e18bee6b8cd (diff) | |
arm_mpam: Fix null pointer dereference when restoring bandwidth counters
When an MSC supporting memory bandwidth monitoring is brought offline and
then online, mpam_restore_mbwu_state() calls __ris_msmon_read() via ipi to
restore the configuration of the bandwidth counters. It doesn't care about
the value read, mbwu_arg.val, and doesn't set it leading to a null pointer
dereference when __ris_msmon_read() adds to it. This results in a kernel
oops with a call trace such as:
Call trace:
__ris_msmon_read+0x19c/0x64c (P)
mpam_restore_mbwu_state+0xa0/0xe8
smp_call_on_cpu_callback+0x1c/0x38
process_one_work+0x154/0x4b4
worker_thread+0x188/0x310
kthread+0x11c/0x130
ret_from_fork+0x10/0x20
Provide a local variable for val to avoid __ris_msmon_read() dereferencing
a null pointer when adding to val.
Fixes: 41e8a14950e1 ("arm_mpam: Track bandwidth counter state for power management")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/resctrl/mpam_devices.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 1eebc2602187..0666be6b0e88 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -1428,6 +1428,7 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris *ris, u16 partid, static int mpam_restore_mbwu_state(void *_ris) { int i; + u64 val; struct mon_read mwbu_arg; struct mpam_msc_ris *ris = _ris; struct mpam_class *class = ris->vmsc->comp->class; @@ -1437,6 +1438,7 @@ static int mpam_restore_mbwu_state(void *_ris) mwbu_arg.ris = ris; mwbu_arg.ctx = &ris->mbwu_state[i].cfg; mwbu_arg.type = mpam_msmon_choose_counter(class); + mwbu_arg.val = &val; __ris_msmon_read(&mwbu_arg); } |