From 8ec462785d6e6dd617ca4cd4a2f4db4d90204ea8 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 19 Jun 2023 08:27:55 +0200 Subject: [PATCH] 5.15-stable patches added patches: cgroup-always-put-cset-in-cgroup_css_set_put_fork.patch rcu-kvfree-avoid-freeing-new-kfree_rcu-memory-after-old-grace-period.patch --- ...-put-cset-in-cgroup_css_set_put_fork.patch | 83 +++++++++ ...ee_rcu-memory-after-old-grace-period.patch | 164 ++++++++++++++++++ queue-5.15/series | 2 + 3 files changed, 249 insertions(+) create mode 100644 queue-5.15/cgroup-always-put-cset-in-cgroup_css_set_put_fork.patch create mode 100644 queue-5.15/rcu-kvfree-avoid-freeing-new-kfree_rcu-memory-after-old-grace-period.patch diff --git a/queue-5.15/cgroup-always-put-cset-in-cgroup_css_set_put_fork.patch b/queue-5.15/cgroup-always-put-cset-in-cgroup_css_set_put_fork.patch new file mode 100644 index 00000000000..a120450f370 --- /dev/null +++ b/queue-5.15/cgroup-always-put-cset-in-cgroup_css_set_put_fork.patch @@ -0,0 +1,83 @@ +From 2bd110339288c18823dcace602b63b0d8627e520 Mon Sep 17 00:00:00 2001 +From: John Sperbeck +Date: Sun, 21 May 2023 19:29:53 +0000 +Subject: cgroup: always put cset in cgroup_css_set_put_fork + +From: John Sperbeck + +commit 2bd110339288c18823dcace602b63b0d8627e520 upstream. + +A successful call to cgroup_css_set_fork() will always have taken +a ref on kargs->cset (regardless of CLONE_INTO_CGROUP), so always +do a corresponding put in cgroup_css_set_put_fork(). + +Without this, a cset and its contained css structures will be +leaked for some fork failures. The following script reproduces +the leak for a fork failure due to exceeding pids.max in the +pids controller. A similar thing can happen if we jump to the +bad_fork_cancel_cgroup label in copy_process(). + +[ -z "$1" ] && echo "Usage $0 pids-root" && exit 1 +PID_ROOT=$1 +CGROUP=$PID_ROOT/foo + +[ -e $CGROUP ] && rmdir -f $CGROUP +mkdir $CGROUP +echo 5 > $CGROUP/pids.max +echo $$ > $CGROUP/cgroup.procs + +fork_bomb() +{ + set -e + for i in $(seq 10); do + /bin/sleep 3600 & + done +} + +(fork_bomb) & +wait +echo $$ > $PID_ROOT/cgroup.procs +kill $(cat $CGROUP/cgroup.procs) +rmdir $CGROUP + +Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups") +Cc: stable@vger.kernel.org # v5.7+ +Signed-off-by: John Sperbeck +Signed-off-by: Tejun Heo +[TJM: This backport accommodates the lack of cgroup_unlock] +Signed-off-by: T.J. Mercier +Signed-off-by: Greg Kroah-Hartman +--- + kernel/cgroup/cgroup.c | 17 ++++++++--------- + 1 file changed, 8 insertions(+), 9 deletions(-) + +--- a/kernel/cgroup/cgroup.c ++++ b/kernel/cgroup/cgroup.c +@@ -6259,19 +6259,18 @@ err: + static void cgroup_css_set_put_fork(struct kernel_clone_args *kargs) + __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex) + { ++ struct cgroup *cgrp = kargs->cgrp; ++ struct css_set *cset = kargs->cset; ++ + cgroup_threadgroup_change_end(current); + +- if (kargs->flags & CLONE_INTO_CGROUP) { +- struct cgroup *cgrp = kargs->cgrp; +- struct css_set *cset = kargs->cset; ++ if (cset) { ++ put_css_set(cset); ++ kargs->cset = NULL; ++ } + ++ if (kargs->flags & CLONE_INTO_CGROUP) { + mutex_unlock(&cgroup_mutex); +- +- if (cset) { +- put_css_set(cset); +- kargs->cset = NULL; +- } +- + if (cgrp) { + cgroup_put(cgrp); + kargs->cgrp = NULL; diff --git a/queue-5.15/rcu-kvfree-avoid-freeing-new-kfree_rcu-memory-after-old-grace-period.patch b/queue-5.15/rcu-kvfree-avoid-freeing-new-kfree_rcu-memory-after-old-grace-period.patch new file mode 100644 index 00000000000..24e9a00c732 --- /dev/null +++ b/queue-5.15/rcu-kvfree-avoid-freeing-new-kfree_rcu-memory-after-old-grace-period.patch @@ -0,0 +1,164 @@ +From 5da7cb193db32da783a3f3e77d8b639989321d48 Mon Sep 17 00:00:00 2001 +From: Ziwei Dai +Date: Fri, 31 Mar 2023 20:42:09 +0800 +Subject: rcu/kvfree: Avoid freeing new kfree_rcu() memory after old grace period + +From: Ziwei Dai + +commit 5da7cb193db32da783a3f3e77d8b639989321d48 upstream. + +Memory passed to kvfree_rcu() that is to be freed is tracked by a +per-CPU kfree_rcu_cpu structure, which in turn contains pointers +to kvfree_rcu_bulk_data structures that contain pointers to memory +that has not yet been handed to RCU, along with an kfree_rcu_cpu_work +structure that tracks the memory that has already been handed to RCU. +These structures track three categories of memory: (1) Memory for +kfree(), (2) Memory for kvfree(), and (3) Memory for both that arrived +during an OOM episode. The first two categories are tracked in a +cache-friendly manner involving a dynamically allocated page of pointers +(the aforementioned kvfree_rcu_bulk_data structures), while the third +uses a simple (but decidedly cache-unfriendly) linked list through the +rcu_head structures in each block of memory. + +On a given CPU, these three categories are handled as a unit, with that +CPU's kfree_rcu_cpu_work structure having one pointer for each of the +three categories. Clearly, new memory for a given category cannot be +placed in the corresponding kfree_rcu_cpu_work structure until any old +memory has had its grace period elapse and thus has been removed. And +the kfree_rcu_monitor() function does in fact check for this. + +Except that the kfree_rcu_monitor() function checks these pointers one +at a time. This means that if the previous kfree_rcu() memory passed +to RCU had only category 1 and the current one has only category 2, the +kfree_rcu_monitor() function will send that current category-2 memory +along immediately. This can result in memory being freed too soon, +that is, out from under unsuspecting RCU readers. + +To see this, consider the following sequence of events, in which: + +o Task A on CPU 0 calls rcu_read_lock(), then uses "from_cset", + then is preempted. + +o CPU 1 calls kfree_rcu(cset, rcu_head) in order to free "from_cset" + after a later grace period. Except that "from_cset" is freed + right after the previous grace period ended, so that "from_cset" + is immediately freed. Task A resumes and references "from_cset"'s + member, after which nothing good happens. + +In full detail: + +CPU 0 CPU 1 +---------------------- ---------------------- +count_memcg_event_mm() +|rcu_read_lock() <--- +|mem_cgroup_from_task() + |// css_set_ptr is the "from_cset" mentioned on CPU 1 + |css_set_ptr = rcu_dereference((task)->cgroups) + |// Hard irq comes, current task is scheduled out. + + cgroup_attach_task() + |cgroup_migrate() + |cgroup_migrate_execute() + |css_set_move_task(task, from_cset, to_cset, true) + |cgroup_move_task(task, to_cset) + |rcu_assign_pointer(.., to_cset) + |... + |cgroup_migrate_finish() + |put_css_set_locked(from_cset) + |from_cset->refcount return 0 + |kfree_rcu(cset, rcu_head) // free from_cset after new gp + |add_ptr_to_bulk_krc_lock() + |schedule_delayed_work(&krcp->monitor_work, ..) + + kfree_rcu_monitor() + |krcp->bulk_head[0]'s work attached to krwp->bulk_head_free[] + |queue_rcu_work(system_wq, &krwp->rcu_work) + |if rwork->rcu.work is not in WORK_STRUCT_PENDING_BIT state, + |call_rcu(&rwork->rcu, rcu_work_rcufn) <--- request new gp + + // There is a perious call_rcu(.., rcu_work_rcufn) + // gp end, rcu_work_rcufn() is called. + rcu_work_rcufn() + |__queue_work(.., rwork->wq, &rwork->work); + + |kfree_rcu_work() + |krwp->bulk_head_free[0] bulk is freed before new gp end!!! + |The "from_cset" is freed before new gp end. + +// the task resumes some time later. + |css_set_ptr->subsys[(subsys_id) <--- Caused kernel crash, because css_set_ptr is freed. + +This commit therefore causes kfree_rcu_monitor() to refrain from moving +kfree_rcu() memory to the kfree_rcu_cpu_work structure until the RCU +grace period has completed for all three categories. + +v2: Use helper function instead of inserted code block at kfree_rcu_monitor(). + +Fixes: 34c881745549 ("rcu: Support kfree_bulk() interface in kfree_rcu()") +Fixes: 5f3c8d620447 ("rcu/tree: Maintain separate array for vmalloc ptrs") +Reported-by: Mukesh Ojha +Signed-off-by: Ziwei Dai +Reviewed-by: Uladzislau Rezki (Sony) +Tested-by: Uladzislau Rezki (Sony) +Signed-off-by: Paul E. McKenney +Signed-off-by: Suren Baghdasaryan +Signed-off-by: Greg Kroah-Hartman +--- + kernel/rcu/tree.c | 39 +++++++++++++++++++++++++++++++-------- + 1 file changed, 31 insertions(+), 8 deletions(-) + +--- a/kernel/rcu/tree.c ++++ b/kernel/rcu/tree.c +@@ -3328,6 +3328,30 @@ static void kfree_rcu_work(struct work_s + } + } + ++static bool ++need_offload_krc(struct kfree_rcu_cpu *krcp) ++{ ++ int i; ++ ++ for (i = 0; i < FREE_N_CHANNELS; i++) ++ if (krcp->bkvhead[i]) ++ return true; ++ ++ return !!krcp->head; ++} ++ ++static bool ++need_wait_for_krwp_work(struct kfree_rcu_cpu_work *krwp) ++{ ++ int i; ++ ++ for (i = 0; i < FREE_N_CHANNELS; i++) ++ if (krwp->bkvhead_free[i]) ++ return true; ++ ++ return !!krwp->head_free; ++} ++ + /* + * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. + */ +@@ -3344,14 +3368,13 @@ static void kfree_rcu_monitor(struct wor + for (i = 0; i < KFREE_N_BATCHES; i++) { + struct kfree_rcu_cpu_work *krwp = &(krcp->krw_arr[i]); + +- // Try to detach bkvhead or head and attach it over any +- // available corresponding free channel. It can be that +- // a previous RCU batch is in progress, it means that +- // immediately to queue another one is not possible so +- // in that case the monitor work is rearmed. +- if ((krcp->bkvhead[0] && !krwp->bkvhead_free[0]) || +- (krcp->bkvhead[1] && !krwp->bkvhead_free[1]) || +- (krcp->head && !krwp->head_free)) { ++ // Try to detach bulk_head or head and attach it, only when ++ // all channels are free. Any channel is not free means at krwp ++ // there is on-going rcu work to handle krwp's free business. ++ if (need_wait_for_krwp_work(krwp)) ++ continue; ++ ++ if (need_offload_krc(krcp)) { + // Channel 1 corresponds to the SLAB-pointer bulk path. + // Channel 2 corresponds to vmalloc-pointer bulk path. + for (j = 0; j < FREE_N_CHANNELS; j++) { diff --git a/queue-5.15/series b/queue-5.15/series index 5ad8bb46ac4..36fdbb2e6fd 100644 --- a/queue-5.15/series +++ b/queue-5.15/series @@ -97,3 +97,5 @@ dm-don-t-lock-fs-when-the-map-is-null-during-suspend.patch net-tipc-resize-nlattr-array-to-correct-size.patch selftests-ptp-fix-timestamp-printf-format-for-ptp_sy.patch afs-fix-vlserver-probe-rtt-handling.patch +cgroup-always-put-cset-in-cgroup_css_set_put_fork.patch +rcu-kvfree-avoid-freeing-new-kfree_rcu-memory-after-old-grace-period.patch -- 2.47.2