Messages in this thread Patch in this message | | | Subject | Re: [PATCH 5.4 000/168] 5.4.25-stable review | From | Holger Hoffstätte <> | Date | Tue, 10 Mar 2020 15:57:17 +0100 |
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On 3/10/20 3:51 PM, Holger Hoffstätte wrote: > On 3/10/20 3:35 PM, Greg Kroah-Hartman wrote: >> On Tue, Mar 10, 2020 at 03:02:37PM +0100, Holger Hoffstätte wrote: >>> On 3/10/20 1:37 PM, Greg Kroah-Hartman wrote: >>>> This is the start of the stable review cycle for the 5.4.25 release. >>> >>> This fails to compile due to broken patch 001/168: >>> "block, bfq: get a ref to a group when adding it to a service tree": >>> >>> .. >>> block/bfq-wf2q.c: In function 'bfq_get_entity': >>> ./include/linux/kernel.h:994:51: error: 'struct bfq_group' has no member named 'entity' >>> .. >>> >>> The calls to bfq_get_entity::bfqg_and_blkg_get and bfq_forget_entity::bfqg_and_blkg_put >>> in bfq-wf2q.c need to be wrapped in #ifdef CONFIG_BFQ_GROUP_IOSCHED, otherwise >>> the build will fail when CONFIG_BFQ_GROUP_IOSCHED is not enabled. >>> This horribly error-prone #ifdef mess was finally removed in upstream commit >>> 4d8340d0d4d9. For 5.4 we'll either need that as well or add them back. >> >> Ick, that's a mess. >> >> I'll go drop that patch now, odd that it passed my build tests... > > Uh, please no? It fixes a rather nasty UAF when cgroups are in use. > Please just add the other upstream commit as well, I confirmed it applies > cleanly and fixes the problem. >
Alternatively I've appended the version originally sent to the mailing list, with those #ifdefs intact. That's what I had in my tree so far, you could consider it a 5.4 backport. Other than that there's no functional difference to the upstream version.
hth, Holger From: Paolo Valente <paolo.valente@linaro.org> To: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, bfq-iosched@googlegroups.com, oleksandr@natalenko.name, patdung100@gmail.com, cevich@redhat.com, Paolo Valente <paolo.valente@linaro.org> Subject: [PATCH BUGFIX 5/6] block, bfq: get a ref to a group when adding it to a service tree Date: Fri, 31 Jan 2020 10:24:08 +0100
BFQ schedules generic entities, which may represent either bfq_queues or groups of bfq_queues. When an entity is inserted into a service tree, a reference must be taken, to make sure that the entity does not disappear while still referred in the tree. Unfortunately, such a reference is mistakenly taken only if the entity represents a bfq_queue. This commit takes a reference also in case the entity represents a group.
Tested-by: Chris Evich <cevich@redhat.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> --- block/bfq-cgroup.c | 2 +- block/bfq-iosched.h | 1 + block/bfq-wf2q.c | 16 +++++++++++++++- 3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index c818c64766e5..f85b25fd06f2 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -332,7 +332,7 @@ static void bfqg_put(struct bfq_group *bfqg) kfree(bfqg); } -static void bfqg_and_blkg_get(struct bfq_group *bfqg) +void bfqg_and_blkg_get(struct bfq_group *bfqg) { /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */ bfqg_get(bfqg); diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index f1cb89def7f8..b9627ec7007b 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -984,6 +984,7 @@ struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); struct bfq_group *bfqq_group(struct bfq_queue *bfqq); struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node); +void bfqg_and_blkg_get(struct bfq_group *bfqg); void bfqg_and_blkg_put(struct bfq_group *bfqg); #ifdef CONFIG_BFQ_GROUP_IOSCHED diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c index 26776bdbdf36..ef06e0d34b5b 100644 --- a/block/bfq-wf2q.c +++ b/block/bfq-wf2q.c @@ -533,7 +533,13 @@ static void bfq_get_entity(struct bfq_entity *entity) bfqq->ref++; bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", bfqq, bfqq->ref); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + } else + bfqg_and_blkg_get(container_of(entity, struct bfq_group, + entity)); +#else } +#endif } /** @@ -647,8 +653,16 @@ static void bfq_forget_entity(struct bfq_service_tree *st, entity->on_st_or_in_serv = false; st->wsum -= entity->weight; - if (bfqq && !is_in_service) + if (is_in_service) + return; + + if (bfqq) bfq_put_queue(bfqq); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + else + bfqg_and_blkg_put(container_of(entity, struct bfq_group, + entity)); +#endif } /** -- 2.20.1
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