On Wed, Jul 01 2015 at 12:57pm -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > bio_integrity_alloc() and bio_integrity_free() assume that if a bio was > allocated from a bioset that that bioset also had its bio_integrity_pool > allocated using bioset_integrity_create(). This is a very bad > assumption given that bioset_create() and bioset_integrity_create() are > completely disjoint. Not all callers of bioset_create() have been > trained to also call bioset_integrity_create() -- and they may not care > to be. > > Fix this by falling back to kmalloc'ing 'struct bio_integrity_payload' > rather than force all bioset consumers to (wastefully) preallocate a > bio_integrity_pool that they very likely won't actually need (given the > niche nature of the current block integrity support). > > Otherwise, a NULL pointer "Kernel BUG" with a trace like the following > will be observed (as seen on s390x using zfcp storage) because dm-io > doesn't use bioset_integrity_create() when creating its bioset: > > [ 791.643338] Call Trace: > [ 791.643339] ([<00000003df98b848>] 0x3df98b848) > [ 791.643341] [<00000000002c5de8>] bio_integrity_alloc+0x48/0xf8 > [ 791.643348] [<00000000002c6486>] bio_integrity_prep+0xae/0x2f0 > [ 791.643349] [<0000000000371e38>] blk_queue_bio+0x1c8/0x3d8 > [ 791.643355] [<000000000036f8d0>] generic_make_request+0xc0/0x100 > [ 791.643357] [<000000000036f9b2>] submit_bio+0xa2/0x198 > [ 791.643406] [<000003ff801f9774>] dispatch_io+0x15c/0x3b0 [dm_mod] > [ 791.643419] [<000003ff801f9b3e>] dm_io+0x176/0x2f0 [dm_mod] > [ 791.643423] [<000003ff8074b28a>] do_reads+0x13a/0x1a8 [dm_mirror] > [ 791.643425] [<000003ff8074b43a>] do_mirror+0x142/0x298 [dm_mirror] > [ 791.643428] [<0000000000154fca>] process_one_work+0x18a/0x3f8 > [ 791.643432] [<000000000015598a>] worker_thread+0x132/0x3b0 > [ 791.643435] [<000000000015d49a>] kthread+0xd2/0xd8 > [ 791.643438] [<00000000005bc0ca>] kernel_thread_starter+0x6/0xc > [ 791.643446] [<00000000005bc0c4>] kernel_thread_starter+0x0/0xc > > Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > block/bio-integrity.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > NOTE: this serves as a more generic fix in the block layer rather than > the dm-io specific fix which isn't ideal (due to potential for memory > waste), see: > https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=17dbe96d4f8a6f87004e6cfb5944872dfe2edb9f > > diff --git a/block/bio-integrity.c b/block/bio-integrity.c > index 0436c21..719b715 100644 > --- a/block/bio-integrity.c > +++ b/block/bio-integrity.c > @@ -51,7 +51,7 @@ struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio, > unsigned long idx = BIO_POOL_NONE; > unsigned inline_vecs; > > - if (!bs) { > + if (!bs || !bs->bio_integrity_pool) { > bip = kmalloc(sizeof(struct bio_integrity_payload) + > sizeof(struct bio_vec) * nr_vecs, gfp_mask); > inline_vecs = nr_vecs; > @@ -104,7 +104,7 @@ void bio_integrity_free(struct bio *bio) > kfree(page_address(bip->bip_vec->bv_page) + > bip->bip_vec->bv_offset); > > - if (bs) { > + if (bs && bs->bio_integrity_pool) { > if (bip->bip_slab != BIO_POOL_NONE) > bvec_free(bs->bvec_integrity_pool, bip->bip_vec, > bip->bip_slab); > -- > 2.3.2 (Apple Git-55) > > Both the above block patch and the referenced dm-io patch fix the following issue. I really prefer the block fix over the dm-io one. As such I'd like to see it go upstream during 4.2-rc. Jens, what do you think? Here is an updated NULL pointer trace using 4.2-rc1 (which is easily hit using the attached reproducer script): [ 239.425111] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048 [ 239.426010] IP: [<ffffffff811b2bb0>] mempool_alloc+0x60/0x180 [ 239.426010] PGD 0 [ 239.426010] Oops: 0000 [#1] SMP [ 239.426010] Modules linked in: dm_mirror dm_region_hash dm_log scsi_debug sg nfsv3 nfs fscache crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel glue_helper lrw gf128mul ablk_helper dm_mod cryptd pcspkr serio_raw virtio_balloon 8139too i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ext4 mbcache jbd2 ata_generic sd_mod pata_acpi cirrus syscopyarea sysfillrect sysimgblt drm_kms_helper virtio_scsi ttm virtio_blk drm ata_piix libata virtio_pci virtio_ring 8139cp virtio mii i2c_core floppy [ 239.426010] CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted 4.2.0-rc1+ #59 [ 239.426010] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 239.426010] Workqueue: kcopyd do_work [dm_mod] [ 239.426010] task: ffff88011a701bc0 ti: ffff880036a10000 task.ti: ffff880036a10000 [ 239.426010] RIP: 0010:[<ffffffff811b2bb0>] [<ffffffff811b2bb0>] mempool_alloc+0x60/0x180 [ 239.426010] RSP: 0018:ffff880036a13878 EFLAGS: 00010206 [ 239.426010] RAX: ffff880036a13888 RBX: ffff88011a701bc0 RCX: 0000000000000000 [ 239.426010] RDX: 0000000000000086 RSI: ffffffff81a88940 RDI: 0000000000000246 [ 239.426010] RBP: ffff880036a138e8 R08: 000000000001a9b0 R09: 0000000000000080 [ 239.426010] R10: ffff88011b001500 R11: 0000000000000000 R12: 0000000000000060 [ 239.426010] R13: ffff880036a138a0 R14: 0000000000011200 R15: 0000000000000000 [ 239.426010] FS: 0000000000000000(0000) GS:ffff88011fd00000(0000) knlGS:0000000000000000 [ 239.426010] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 239.426010] CR2: 0000000000000048 CR3: 00000000d8797000 CR4: 00000000000407e0 [ 239.426010] Stack: [ 239.426010] 0000000000000001 0001121000000010 ffffffff81a88940 ffff88011b001500 [ 239.426010] ffff880036a138c8 ffffffff810e01cd 00000000000004f2 00000000627d6696 [ 239.426010] 0000000000000246 0000000000000400 ffff8800da8cfd00 0000000000000010 [ 239.426010] Call Trace: [ 239.426010] [<ffffffff810e01cd>] ? __lock_is_held+0x4d/0x70 [ 239.426010] [<ffffffff8136b00f>] bio_integrity_alloc+0x4f/0x1d0 [ 239.426010] [<ffffffff8136b803>] bio_integrity_prep+0xc3/0x220 [ 239.426010] [<ffffffff8134c56f>] blk_sq_make_request+0x10f/0x570 [ 239.426010] [<ffffffff810e01cd>] ? __lock_is_held+0x4d/0x70 [ 239.426010] [<ffffffff8133b236>] generic_make_request+0xd6/0x110 [ 239.426010] [<ffffffff8133b2e7>] submit_bio+0x77/0x150 [ 239.426010] [<ffffffff81335a3f>] ? bio_alloc_bioset+0x1df/0x2e0 [ 239.426010] [<ffffffffa036cd48>] dispatch_io+0x1a8/0x3a0 [dm_mod] [ 239.426010] [<ffffffffa036c840>] ? dm_copy_name_and_uuid+0xc0/0xc0 [dm_mod] [ 239.426010] [<ffffffffa036c870>] ? list_get_page+0x30/0x30 [dm_mod] [ 239.426010] [<ffffffffa036d7eb>] ? run_io_job+0x9b/0x190 [dm_mod] [ 239.426010] [<ffffffffa036d4c0>] ? dm_kcopyd_do_callback+0x50/0x50 [dm_mod] [ 239.426010] [<ffffffffa036d183>] dm_io+0x103/0x210 [dm_mod] [ 239.426010] [<ffffffffa036c840>] ? dm_copy_name_and_uuid+0xc0/0xc0 [dm_mod] [ 239.426010] [<ffffffffa036c870>] ? list_get_page+0x30/0x30 [dm_mod] [ 239.426010] [<ffffffffa036d834>] run_io_job+0xe4/0x190 [dm_mod] [ 239.426010] [<ffffffffa036d4c0>] ? dm_kcopyd_do_callback+0x50/0x50 [dm_mod] [ 239.426010] [<ffffffffa036da7a>] process_jobs+0x5a/0x100 [dm_mod] [ 239.426010] [<ffffffffa036d750>] ? segment_complete+0x170/0x170 [dm_mod] [ 239.426010] [<ffffffffa036db91>] do_work+0x71/0xa0 [dm_mod] [ 239.426010] [<ffffffff810a79d7>] process_one_work+0x1e7/0x7e0 [ 239.426010] [<ffffffff810a794a>] ? process_one_work+0x15a/0x7e0 [ 239.426010] [<ffffffff810a80e4>] worker_thread+0x114/0x460 [ 239.426010] [<ffffffff810a7fd0>] ? process_one_work+0x7e0/0x7e0 [ 239.426010] [<ffffffff810aebd7>] kthread+0x107/0x120 [ 239.426010] [<ffffffff817065f0>] ? _raw_spin_unlock_irq+0x30/0x50 [ 239.426010] [<ffffffff810aead0>] ? kthread_create_on_node+0x240/0x240 [ 239.426010] [<ffffffff8170731f>] ret_from_fork+0x3f/0x70 [ 239.426010] [<ffffffff810aead0>] ? kthread_create_on_node+0x240/0x240 [ 239.426010] Code: d8 83 e3 af 4d 8d 67 60 0d 00 12 01 00 41 89 de 89 45 9c 48 8d 45 a0 41 81 ce 00 12 01 00 65 48 8b 1c 25 00 ba 00 00 4c 8d 68 18 <49> 8b 77 48 44 89 f7 41 ff 57 50 48 85 c0 74 45 48 8b 4d c8 65 [ 239.426010] RIP [<ffffffff811b2bb0>] mempool_alloc+0x60/0x180 [ 239.426010] RSP <ffff880036a13878> [ 239.426010] CR2: 0000000000000048 [ 239.426010] ---[ end trace a4a18906f4031b09 ]---
Attachment:
bip_bioset_NULL_ptr.sh
Description: Bourne shell script
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