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Add file system lecture #57

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Add file system lecture #57

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@razvand razvand commented Apr 23, 2018

Add lecture on file system, VFS and a pinch of block I/O layer.

tavip pushed a commit to linux-kernel-labs/linux-kernel-labs.github.io that referenced this pull request Apr 23, 2018
@razvand razvand requested review from dbaluta and tavip April 23, 2018 19:38
@razvand razvand closed this Apr 24, 2018
@razvand razvand deleted the fs branch April 24, 2018 15:02
@razvand razvand restored the fs branch April 24, 2018 15:03
tavip pushed a commit to linux-kernel-labs/linux-kernel-labs.github.io that referenced this pull request Apr 24, 2018
@razvand razvand deleted the fs branch March 16, 2019 08:43
dbaluta pushed a commit to dbaluta/linux that referenced this pull request Jun 5, 2019
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
linux-kernel-labs#42: FILE: fs/ocfs2/aops.c:2155:
+	unsigned i_blkbits = inode->i_sb->s_blocksize_bits;

ERROR: code indent should use tabs where possible
linux-kernel-labs#53: FILE: fs/ocfs2/aops.c:2166:
+ ^I * "pos" and "end", we need map twice to return different buffer state:$

WARNING: please, no space before tabs
linux-kernel-labs#53: FILE: fs/ocfs2/aops.c:2166:
+ ^I * "pos" and "end", we need map twice to return different buffer state:$

ERROR: code indent should use tabs where possible
linux-kernel-labs#54: FILE: fs/ocfs2/aops.c:2167:
+ ^I * 1. area in file size, not set NEW;$

WARNING: please, no space before tabs
linux-kernel-labs#54: FILE: fs/ocfs2/aops.c:2167:
+ ^I * 1. area in file size, not set NEW;$

ERROR: code indent should use tabs where possible
linux-kernel-labs#55: FILE: fs/ocfs2/aops.c:2168:
+ ^I * 2. area out file size, set  NEW.$

WARNING: please, no space before tabs
linux-kernel-labs#55: FILE: fs/ocfs2/aops.c:2168:
+ ^I * 2. area out file size, set  NEW.$

ERROR: code indent should use tabs where possible
linux-kernel-labs#56: FILE: fs/ocfs2/aops.c:2169:
+ ^I *$

WARNING: please, no space before tabs
linux-kernel-labs#56: FILE: fs/ocfs2/aops.c:2169:
+ ^I *$

ERROR: code indent should use tabs where possible
linux-kernel-labs#57: FILE: fs/ocfs2/aops.c:2170:
+ ^I *^I^I   iblock    endblk$

WARNING: please, no space before tabs
linux-kernel-labs#57: FILE: fs/ocfs2/aops.c:2170:
+ ^I *^I^I   iblock    endblk$

ERROR: code indent should use tabs where possible
linux-kernel-labs#58: FILE: fs/ocfs2/aops.c:2171:
+ ^I * |--------|---------|---------|---------$

WARNING: please, no space before tabs
linux-kernel-labs#58: FILE: fs/ocfs2/aops.c:2171:
+ ^I * |--------|---------|---------|---------$

ERROR: code indent should use tabs where possible
linux-kernel-labs#59: FILE: fs/ocfs2/aops.c:2172:
+ ^I * |<-------area in file------->|$

WARNING: please, no space before tabs
linux-kernel-labs#59: FILE: fs/ocfs2/aops.c:2172:
+ ^I * |<-------area in file------->|$

ERROR: code indent should use tabs where possible
linux-kernel-labs#60: FILE: fs/ocfs2/aops.c:2173:
+ ^I */$

WARNING: please, no space before tabs
linux-kernel-labs#60: FILE: fs/ocfs2/aops.c:2173:
+ ^I */$

total: 8 errors, 9 warnings, 40 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

NOTE: Whitespace errors detected.
      You may wish to use scripts/cleanpatch or scripts/cleanfile

./patches/ocfs2-clear-zero-in-unaligned-direct-io.patch has style problems, please review.

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Jia Guo <[email protected]>
Cc: Yiwen Jiang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
dbaluta pushed a commit to dbaluta/linux that referenced this pull request Sep 28, 2019
Hangbin Liu says:

====================
fix dev null pointer dereference when send packets larger than mtu in collect_md mode

When we send a packet larger than PMTU, we need to reply with
icmp_send(ICMP_FRAG_NEEDED) or icmpv6_send(ICMPV6_PKT_TOOBIG).

But with collect_md mode, kernel will crash while accessing the dst dev
as __metadata_dst_init() init dst->dev to NULL by default. Here is what
the code path looks like, for GRE:

- ip6gre_tunnel_xmit
  - ip6gre_xmit_ipv4
    - __gre6_xmit
      - ip6_tnl_xmit
        - if skb->len - t->tun_hlen - eth_hlen > mtu; return -EMSGSIZE
    - icmp_send
      - net = dev_net(rt->dst.dev); <-- here
  - ip6gre_xmit_ipv6
    - __gre6_xmit
      - ip6_tnl_xmit
        - if skb->len - t->tun_hlen - eth_hlen > mtu; return -EMSGSIZE
    - icmpv6_send
      ...
      - decode_session4
        - oif = skb_dst(skb)->dev->ifindex; <-- here
      - decode_session6
        - oif = skb_dst(skb)->dev->ifindex; <-- here

We could not fix it in __metadata_dst_init() as there is no dev supplied.
Look in to the __icmp_send()/decode_session{4,6} code we could find the dst
dev is actually not needed. In __icmp_send(), we could get the net by skb->dev.
For decode_session{4,6}, as it was called by xfrm_decode_session_reverse()
in this scenario, the oif is not used by
fl4->flowi4_oif = reverse ? skb->skb_iif : oif;

The reproducer is easy:

ovs-vsctl add-br br0
ip link set br0 up
ovs-vsctl add-port br0 gre0 -- set interface gre0 type=gre options:remote_ip=$dst_addr
ip link set gre0 up
ip addr add ${local_gre6}/64 dev br0
ping6 $remote_gre6 -s 1500

The kernel will crash like
[40595.821651] BUG: kernel NULL pointer dereference, address: 0000000000000108
[40595.822411] #PF: supervisor read access in kernel mode
[40595.822949] #PF: error_code(0x0000) - not-present page
[40595.823492] PGD 0 P4D 0
[40595.823767] Oops: 0000 [#1] SMP PTI
[40595.824139] CPU: 0 PID: 2831 Comm: handler12 Not tainted 5.2.0 linux-kernel-labs#57
[40595.824788] Hardware name: Red Hat KVM, BIOS 1.11.1-3.module+el8.1.0+2983+b2ae9c0a 04/01/2014
[40595.825680] RIP: 0010:__xfrm_decode_session+0x6b/0x930
[40595.826219] Code: b7 c0 00 00 00 b8 06 00 00 00 66 85 d2 0f b7 ca 48 0f 45 c1 44 0f b6 2c 06 48 8b 47 58 48 83 e0 fe 0f 84 f4 04 00 00 48 8b 00 <44> 8b 80 08 01 00 00 41 f6 c4 01 4c 89 e7
ba 58 00 00 00 0f 85 47
[40595.828155] RSP: 0018:ffffc90000a73438 EFLAGS: 00010286
[40595.828705] RAX: 0000000000000000 RBX: ffff8881329d7100 RCX: 0000000000000000
[40595.829450] RDX: 0000000000000000 RSI: ffff8881339e70ce RDI: ffff8881329d7100
[40595.830191] RBP: ffffc90000a73470 R08: 0000000000000000 R09: 000000000000000a
[40595.830936] R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90000a73490
[40595.831682] R13: 000000000000002c R14: ffff888132ff1301 R15: ffff8881329d7100
[40595.832427] FS:  00007f5bfcfd6700(0000) GS:ffff88813ba00000(0000) knlGS:0000000000000000
[40595.833266] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[40595.833883] CR2: 0000000000000108 CR3: 000000013a368000 CR4: 00000000000006f0
[40595.834633] Call Trace:
[40595.835392]  ? rt6_multipath_hash+0x4c/0x390
[40595.835853]  icmpv6_route_lookup+0xcb/0x1d0
[40595.836296]  ? icmpv6_xrlim_allow+0x3e/0x140
[40595.836751]  icmp6_send+0x537/0x840
[40595.837125]  icmpv6_send+0x20/0x30
[40595.837494]  tnl_update_pmtu.isra.27+0x19d/0x2a0 [ip_tunnel]
[40595.838088]  ip_md_tunnel_xmit+0x1b6/0x510 [ip_tunnel]
[40595.838633]  gre_tap_xmit+0x10c/0x160 [ip_gre]
[40595.839103]  dev_hard_start_xmit+0x93/0x200
[40595.839551]  sch_direct_xmit+0x101/0x2d0
[40595.839967]  __dev_queue_xmit+0x69f/0x9c0
[40595.840399]  do_execute_actions+0x1717/0x1910 [openvswitch]
[40595.840987]  ? validate_set.isra.12+0x2f5/0x3d0 [openvswitch]
[40595.841596]  ? reserve_sfa_size+0x31/0x130 [openvswitch]
[40595.842154]  ? __ovs_nla_copy_actions+0x1b4/0xad0 [openvswitch]
[40595.842778]  ? __kmalloc_reserve.isra.50+0x2e/0x80
[40595.843285]  ? should_failslab+0xa/0x20
[40595.843696]  ? __kmalloc+0x188/0x220
[40595.844078]  ? __alloc_skb+0x97/0x270
[40595.844472]  ovs_execute_actions+0x47/0x120 [openvswitch]
[40595.845041]  ovs_packet_cmd_execute+0x27d/0x2b0 [openvswitch]
[40595.845648]  genl_family_rcv_msg+0x3a8/0x430
[40595.846101]  genl_rcv_msg+0x47/0x90
[40595.846476]  ? __alloc_skb+0x83/0x270
[40595.846866]  ? genl_family_rcv_msg+0x430/0x430
[40595.847335]  netlink_rcv_skb+0xcb/0x100
[40595.847777]  genl_rcv+0x24/0x40
[40595.848113]  netlink_unicast+0x17f/0x230
[40595.848535]  netlink_sendmsg+0x2ed/0x3e0
[40595.848951]  sock_sendmsg+0x4f/0x60
[40595.849323]  ___sys_sendmsg+0x2bd/0x2e0
[40595.849733]  ? sock_poll+0x6f/0xb0
[40595.850098]  ? ep_scan_ready_list.isra.14+0x20b/0x240
[40595.850634]  ? _cond_resched+0x15/0x30
[40595.851032]  ? ep_poll+0x11b/0x440
[40595.851401]  ? _copy_to_user+0x22/0x30
[40595.851799]  __sys_sendmsg+0x58/0xa0
[40595.852180]  do_syscall_64+0x5b/0x190
[40595.852574]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[40595.853105] RIP: 0033:0x7f5c00038c7d
[40595.853489] Code: c7 20 00 00 75 10 b8 2e 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 8e f7 ff ff 48 89 04 24 b8 2e 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 d7 f7 ff ff 48 89
d0 48 83 c4 08 48 3d 01
[40595.855443] RSP: 002b:00007f5bfcf73c00 EFLAGS: 00003293 ORIG_RAX: 000000000000002e
[40595.856244] RAX: ffffffffffffffda RBX: 00007f5bfcf74a60 RCX: 00007f5c00038c7d
[40595.856990] RDX: 0000000000000000 RSI: 00007f5bfcf73c60 RDI: 0000000000000015
[40595.857736] RBP: 0000000000000004 R08: 0000000000000b7c R09: 0000000000000110
[40595.858613] R10: 0001000800050004 R11: 0000000000003293 R12: 000055c2d8329da0
[40595.859401] R13: 00007f5bfcf74120 R14: 0000000000000347 R15: 00007f5bfcf73c60
[40595.860185] Modules linked in: ip_gre ip_tunnel gre openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 sunrpc bochs_drm ttm drm_kms_helper drm pcspkr joydev i2c_piix4 qemu_fw_cfg xfs libcrc32c virtio_net net_failover serio_raw failover ata_generic virtio_blk pata_acpi floppy
[40595.863155] CR2: 0000000000000108
[40595.863551] ---[ end trace 22209bbcacb4addd ]---

v4: Julian Anastasov remind skb->dev also could be NULL in icmp_send. We'd
better still use dst.dev and do a check to avoid crash.

v3: only replace pkg to packets in cover letter. So I didn't update the version
info in the follow up patches.

v2: fix it in __icmp_send() and decode_session{4,6} separately instead of
updating shared dst dev in {ip_md, ip6}_tunnel_xmit.
====================

Signed-off-by: David S. Miller <[email protected]>
dbaluta pushed a commit to dbaluta/linux that referenced this pull request Jun 17, 2020
Here's the KASAN report:
BUG: KASAN: use-after-free in skcipher_crypt_done+0xe8/0x1a8
Read of size 1 at addr ffff00002304001c by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc1-00162-gfcb90d5 linux-kernel-labs#57
Hardware name: LS1046A RDB Board (DT)
Call trace:
 dump_backtrace+0x0/0x260
 show_stack+0x14/0x20
 dump_stack+0xe8/0x144
 print_address_description.isra.11+0x64/0x348
 __kasan_report+0x11c/0x230
 kasan_report+0xc/0x18
 __asan_load1+0x5c/0x68
 skcipher_crypt_done+0xe8/0x1a8
 caam_jr_dequeue+0x390/0x608
 tasklet_action_common.isra.13+0x1ec/0x230
 tasklet_action+0x24/0x30
 efi_header_end+0x1a4/0x370
 irq_exit+0x114/0x128
 __handle_domain_irq+0x80/0xe0
 gic_handle_irq+0x50/0xa0
 el1_irq+0xb8/0x180
 _raw_spin_unlock_irq+0x2c/0x78
 finish_task_switch+0xa4/0x2f8
 __schedule+0x3a4/0x890
 schedule_idle+0x28/0x50
 do_idle+0x22c/0x338
 cpu_startup_entry+0x24/0x40
 rest_init+0xf8/0x10c
 arch_call_rest_init+0xc/0x14
 start_kernel+0x774/0x7b4

Allocated by task 263:
 save_stack+0x24/0xb0
 __kasan_kmalloc.isra.10+0xc4/0xe0
 kasan_kmalloc+0xc/0x18
 __kmalloc+0x178/0x2b8
 skcipher_edesc_alloc+0x21c/0x1018
 skcipher_encrypt+0x84/0x150
 crypto_skcipher_encrypt+0x50/0x68
 test_skcipher_vec_cfg+0x4d4/0xc10
 test_skcipher_vec+0xf8/0x1d8
 alg_test_skcipher+0xec/0x230
 alg_test.part.44+0x114/0x4a0
 alg_test+0x1c/0x60
 cryptomgr_test+0x34/0x58
 kthread+0x1b8/0x1c0
 ret_from_fork+0x10/0x18

Freed by task 0:
 save_stack+0x24/0xb0
 __kasan_slab_free+0x10c/0x188
 kasan_slab_free+0x10/0x18
 kfree+0x7c/0x298
 skcipher_crypt_done+0xe0/0x1a8
 caam_jr_dequeue+0x390/0x608
 tasklet_action_common.isra.13+0x1ec/0x230
 tasklet_action+0x24/0x30
 efi_header_end+0x1a4/0x370

The buggy address belongs to the object at ffff000023040000
 which belongs to the cache dma-kmalloc-512 of size 512
The buggy address is located 28 bytes inside of
 512-byte region [ffff000023040000, ffff000023040200)
The buggy address belongs to the page:
page:fffffe00006c1000 refcount:1 mapcount:0 mapping:ffff00093200c400 index:0x0 compound_mapcount: 0
flags: 0xffff00000010200(slab|head)
raw: 0ffff00000010200 dead000000000100 dead000000000122 ffff00093200c400
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff00002303ff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff00002303ff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff000023040000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff000023040080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff000023040100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Fixes: ee38767 ("crypto: caam - support crypto_engine framework for SKCIPHER algorithms")
Signed-off-by: Iuliana Prodan <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
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