| Message ID | 20200916035315.34046-3-ebiggers@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: fix up bio_crypt_ctx allocation | expand |
On Tue, Sep 15, 2020 at 08:53:14PM -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > blk_crypto_rq_bio_prep() assumes its gfp_mask argument always includes > __GFP_DIRECT_RECLAIM, so that the mempool_alloc() will always succeed. > > However, blk_crypto_rq_bio_prep() might be called with GFP_ATOMIC via > setup_clone() in drivers/md/dm-rq.c. > > This case isn't currently reachable with a bio that actually has an > encryption context. However, it's fragile to rely on this. Just make > blk_crypto_rq_bio_prep() able to fail. > > Cc: Miaohe Lin <linmiaohe@huawei.com> > Suggested-by: Satya Tangirala <satyat@google.com> > Signed-off-by: Eric Biggers <ebiggers@google.com> > --- > block/blk-core.c | 8 +++++--- > block/blk-crypto-internal.h | 21 ++++++++++++++++----- > block/blk-crypto.c | 18 +++++++----------- > block/blk-mq.c | 7 ++++++- > 4 files changed, 34 insertions(+), 20 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index ca3f0f00c9435..fbeaa49f6fe2c 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -1620,8 +1620,10 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src, > if (rq->bio) { > rq->biotail->bi_next = bio; > rq->biotail = bio; > - } else > + } else { > rq->bio = rq->biotail = bio; > + } > + bio = NULL; > } > > /* Copy attributes of the original request to the clone request. */ > @@ -1634,8 +1636,8 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src, > rq->nr_phys_segments = rq_src->nr_phys_segments; > rq->ioprio = rq_src->ioprio; > > - if (rq->bio) > - blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask); > + if (rq->bio && blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask) < 0) > + goto free_and_out; > > return 0; > > diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h > index d2b0f565d83cb..0d36aae538d7b 100644 > --- a/block/blk-crypto-internal.h > +++ b/block/blk-crypto-internal.h > @@ -142,13 +142,24 @@ static inline void blk_crypto_free_request(struct request *rq) > __blk_crypto_free_request(rq); > } > > -void __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, > - gfp_t gfp_mask); > -static inline void blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, > - gfp_t gfp_mask) > +int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, > + gfp_t gfp_mask); > +/** > + * blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio > + * is inserted > + * @rq: The request to prepare > + * @bio: The first bio being inserted into the request > + * @gfp_mask: Memory allocation flags > + * > + * Return: 0 on success, -ENOMEM if out of memory. -ENOMEM is only possible if > + * @gfp_mask doesn't include %__GFP_DIRECT_RECLAIM. > + */ > +static inline int blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, > + gfp_t gfp_mask) > { > if (bio_has_crypt_ctx(bio)) > - __blk_crypto_rq_bio_prep(rq, bio, gfp_mask); > + return __blk_crypto_rq_bio_prep(rq, bio, gfp_mask); > + return 0; > } > > /** > diff --git a/block/blk-crypto.c b/block/blk-crypto.c > index a3f27a19067c9..bbe7974fd74f0 100644 > --- a/block/blk-crypto.c > +++ b/block/blk-crypto.c > @@ -283,20 +283,16 @@ bool __blk_crypto_bio_prep(struct bio **bio_ptr) > return false; > } > > -/** > - * __blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio > - * is inserted > - * > - * @rq: The request to prepare > - * @bio: The first bio being inserted into the request > - * @gfp_mask: gfp mask > - */ > -void __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, > - gfp_t gfp_mask) > +int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, > + gfp_t gfp_mask) > { > - if (!rq->crypt_ctx) > + if (!rq->crypt_ctx) { > rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); > + if (!rq->crypt_ctx) > + return -ENOMEM; > + } > *rq->crypt_ctx = *bio->bi_crypt_context; > + return 0; > } > > /** > diff --git a/block/blk-mq.c b/block/blk-mq.c > index e04b759add758..9ec0e7149ae69 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -1940,13 +1940,18 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) > static void blk_mq_bio_to_request(struct request *rq, struct bio *bio, > unsigned int nr_segs) > { > + int err; > + > if (bio->bi_opf & REQ_RAHEAD) > rq->cmd_flags |= REQ_FAILFAST_MASK; > > rq->__sector = bio->bi_iter.bi_sector; > rq->write_hint = bio->bi_write_hint; > blk_rq_bio_prep(rq, bio, nr_segs); > - blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO); > + > + /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */ > + err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO); > + WARN_ON_ONCE(err); > > blk_account_io_start(rq); > } Looks good! Reviewed-by: Satya Tangirala <satyat@google.com> > -- > 2.28.0 >
On Tue, Sep 15 2020 at 11:53pm -0400, Eric Biggers <ebiggers@kernel.org> wrote: > From: Eric Biggers <ebiggers@google.com> > > blk_crypto_rq_bio_prep() assumes its gfp_mask argument always includes > __GFP_DIRECT_RECLAIM, so that the mempool_alloc() will always succeed. > > However, blk_crypto_rq_bio_prep() might be called with GFP_ATOMIC via > setup_clone() in drivers/md/dm-rq.c. > > This case isn't currently reachable with a bio that actually has an > encryption context. However, it's fragile to rely on this. Just make > blk_crypto_rq_bio_prep() able to fail. > > Cc: Miaohe Lin <linmiaohe@huawei.com> > Suggested-by: Satya Tangirala <satyat@google.com> > Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/block/blk-core.c b/block/blk-core.c index ca3f0f00c9435..fbeaa49f6fe2c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1620,8 +1620,10 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src, if (rq->bio) { rq->biotail->bi_next = bio; rq->biotail = bio; - } else + } else { rq->bio = rq->biotail = bio; + } + bio = NULL; } /* Copy attributes of the original request to the clone request. */ @@ -1634,8 +1636,8 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src, rq->nr_phys_segments = rq_src->nr_phys_segments; rq->ioprio = rq_src->ioprio; - if (rq->bio) - blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask); + if (rq->bio && blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask) < 0) + goto free_and_out; return 0; diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h index d2b0f565d83cb..0d36aae538d7b 100644 --- a/block/blk-crypto-internal.h +++ b/block/blk-crypto-internal.h @@ -142,13 +142,24 @@ static inline void blk_crypto_free_request(struct request *rq) __blk_crypto_free_request(rq); } -void __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, - gfp_t gfp_mask); -static inline void blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, - gfp_t gfp_mask) +int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, + gfp_t gfp_mask); +/** + * blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio + * is inserted + * @rq: The request to prepare + * @bio: The first bio being inserted into the request + * @gfp_mask: Memory allocation flags + * + * Return: 0 on success, -ENOMEM if out of memory. -ENOMEM is only possible if + * @gfp_mask doesn't include %__GFP_DIRECT_RECLAIM. + */ +static inline int blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, + gfp_t gfp_mask) { if (bio_has_crypt_ctx(bio)) - __blk_crypto_rq_bio_prep(rq, bio, gfp_mask); + return __blk_crypto_rq_bio_prep(rq, bio, gfp_mask); + return 0; } /** diff --git a/block/blk-crypto.c b/block/blk-crypto.c index a3f27a19067c9..bbe7974fd74f0 100644 --- a/block/blk-crypto.c +++ b/block/blk-crypto.c @@ -283,20 +283,16 @@ bool __blk_crypto_bio_prep(struct bio **bio_ptr) return false; } -/** - * __blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio - * is inserted - * - * @rq: The request to prepare - * @bio: The first bio being inserted into the request - * @gfp_mask: gfp mask - */ -void __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, - gfp_t gfp_mask) +int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, + gfp_t gfp_mask) { - if (!rq->crypt_ctx) + if (!rq->crypt_ctx) { rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); + if (!rq->crypt_ctx) + return -ENOMEM; + } *rq->crypt_ctx = *bio->bi_crypt_context; + return 0; } /** diff --git a/block/blk-mq.c b/block/blk-mq.c index e04b759add758..9ec0e7149ae69 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1940,13 +1940,18 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) static void blk_mq_bio_to_request(struct request *rq, struct bio *bio, unsigned int nr_segs) { + int err; + if (bio->bi_opf & REQ_RAHEAD) rq->cmd_flags |= REQ_FAILFAST_MASK; rq->__sector = bio->bi_iter.bi_sector; rq->write_hint = bio->bi_write_hint; blk_rq_bio_prep(rq, bio, nr_segs); - blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO); + + /* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */ + err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO); + WARN_ON_ONCE(err); blk_account_io_start(rq); }