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Greg Thelen f8e9ec1661 block: tolerate tracing of NULL bio
__get_request() can call trace_block_getrq() with bio=NULL which causes
block_get_rq::TP_fast_assign() to deref a NULL pointer and panic.

Syzkaller fuzzer panics with
linux-next (1d53d908b79d7870d89063062584eead4cf83448):
  kasan: GPF could be caused by NULL-ptr deref or user memory access
  general protection fault: 0000 [#1] SMP KASAN
  Modules linked in:
  CPU: 0 PID: 2983 Comm: syzkaller401111 Not tainted 4.13.0-rc7-next-20170901+ #13
  task: ffff8801cf1da000 task.stack: ffff8801ce440000
  RIP: 0010:perf_trace_block_get_rq+0x697/0x970 include/trace/events/block.h:384
  RSP: 0018:ffff8801ce4473f0 EFLAGS: 00010246
  RAX: ffff8801cf1da000 RBX: 1ffff10039c88e84 RCX: 1ffffd1ffff84d27
  RDX: dffffc0000000001 RSI: 1ffff1003b643e7a RDI: ffffe8ffffc26938
  RBP: ffff8801ce447530 R08: 1ffff1003b643e6c R09: ffffe8ffffc26964
  R10: 0000000000000002 R11: fffff91ffff84d2d R12: ffffe8ffffc1f890
  R13: ffffe8ffffc26930 R14: ffffffff85cad9e0 R15: 0000000000000000
  FS:  0000000002641880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000000000043e670 CR3: 00000001d1d7a000 CR4: 00000000001406f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
    trace_block_getrq include/trace/events/block.h:423 [inline]
    __get_request block/blk-core.c:1283 [inline]
    get_request+0x1518/0x23b0 block/blk-core.c:1355
    blk_old_get_request block/blk-core.c:1402 [inline]
    blk_get_request+0x1d8/0x3c0 block/blk-core.c:1427
    sg_scsi_ioctl+0x117/0x750 block/scsi_ioctl.c:451
    sg_ioctl+0x192d/0x2ed0 drivers/scsi/sg.c:1070
    vfs_ioctl fs/ioctl.c:45 [inline]
    do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
    SYSC_ioctl fs/ioctl.c:700 [inline]
    SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
    entry_SYSCALL_64_fastpath+0x1f/0xbe

block_get_rq::TP_fast_assign() has multiple redundant ->dev assignments.
Only one of them is NULL tolerant.  Favor the NULL tolerant one.

Fixes: 74d46992e0 ("block: replace bi_bdev with a gendisk pointer and partitions index")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-09-11 09:45:52 -06:00
Documentation Revert "firmware: add sanity check on shutdown/suspend" 2017-09-10 21:19:06 -07:00
arch Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2017-09-10 21:07:39 -07:00
block Merge branch 'for-4.14/block-postmerge' of git://git.kernel.dk/linux-block 2017-09-09 12:49:01 -07:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: af_alg - get_page upon reassignment to TX SGL 2017-08-22 15:03:27 +08:00
drivers Revert "firmware: add sanity check on shutdown/suspend" 2017-09-10 21:19:06 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs MTD changes for 4.14: 2017-09-09 14:48:21 -07:00
include block: tolerate tracing of NULL bio 2017-09-11 09:45:52 -06:00
init init/main.c: extract early boot entropy from the passed cmdline 2017-09-08 18:26:50 -07:00
ipc ipc: optimize semget/shmget/msgget for lots of keys 2017-09-08 18:26:51 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-09 11:05:20 -07:00
lib cpumask: make cpumask_next() out-of-line 2017-09-08 18:26:51 -07:00
mm mem/memcg: cache rightmost node 2017-09-08 18:26:49 -07:00
net More RDMA work and some op-structure constification from Chuck Lever, 2017-09-09 13:31:49 -07:00
samples media updates for v4.14-rc1 2017-09-07 12:53:14 -07:00
scripts Merge branch 'akpm' (patches from Andrew) 2017-09-09 10:30:07 -07:00
security audit/stable-4.14 PR 20170907 2017-09-07 20:48:25 -07:00
sound linux/kernel.h: move DIV_ROUND_DOWN_ULL() macro 2017-09-08 18:26:47 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-09 11:05:20 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt First batch of KVM changes for 4.14 2017-09-08 15:18:36 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS PCI: Fix typos and whitespace errors 2017-09-01 16:35:50 -05:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS ARM: SoC driver updates for v4.14 2017-09-10 20:40:00 -07:00
Makefile Merge branch 'docs-next' of git://git.lwn.net/linux 2017-09-03 21:07:29 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.