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linux/fs/nilfs2
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Ryusuke Konishi 8301c719a2 nilfs2: fix null pointer dereference at nilfs_segctor_do_construct() 
After commit c3aab9a0bd ("mm/filemap.c: don't initiate writeback if
mapping has no dirty pages"), the following null pointer dereference has
been reported on nilfs2:

  BUG: kernel NULL pointer dereference, address: 00000000000000a8
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP PTI
  ...
  RIP: 0010:percpu_counter_add_batch+0xa/0x60
  ...
  Call Trace:
    __test_set_page_writeback+0x2d3/0x330
    nilfs_segctor_do_construct+0x10d3/0x2110 [nilfs2]
    nilfs_segctor_construct+0x168/0x260 [nilfs2]
    nilfs_segctor_thread+0x127/0x3b0 [nilfs2]
    kthread+0xf8/0x130
    ...

This crash turned out to be caused by set_page_writeback() call for
segment summary buffers at nilfs_segctor_prepare_write().

set_page_writeback() can call inc_wb_stat(inode_to_wb(inode),
WB_WRITEBACK) where inode_to_wb(inode) is NULL if the inode of
underlying block device does not have an associated wb.

This fixes the issue by calling inode_attach_wb() in advance to ensure
to associate the bdev inode with its wb.

Fixes: c3aab9a0bd ("mm/filemap.c: don't initiate writeback if mapping has no dirty pages")
Reported-by: Walton Hoops <me@waltonhoops.com>
Reported-by: Tomas Hlavaty <tom@logand.com>
Reported-by: ARAI Shun-ichi <hermes@ceres.dti.ne.jp>
Reported-by: Hideki EIRAKU <hdk1983@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>	[5.4+]
Link: http://lkml.kernel.org/r/20200608.011819.1399059588922299158.konishi.ryusuke@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-10 19:14:17 -07:00
..
alloc.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
alloc.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
bmap.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
bmap.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
btnode.c XArray: Change xa_insert to return -EBUSY 2019-02-06 13:12:15 -05:00
btnode.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
btree.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
btree.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
cpfile.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
cpfile.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
dat.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
dat.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
dir.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
direct.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
direct.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
export.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
file.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
gcinode.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
ifile.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
ifile.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
inode.c A lot of bug fixes and cleanups for ext4, including: 2020-06-05 16:19:28 -07:00
ioctl.c fs: compat_ioctl: move FITRIM emulation into file systems 2019-10-23 17:23:46 +02:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mdt.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
mdt.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
namei.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
nilfs.h nilfs2: switch to ->free_inode() 2019-05-01 22:43:25 -04:00
page.c nilfs2: Convert to XArray 2018-10-21 10:46:42 -04:00
page.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
recovery.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
segbuf.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
segbuf.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
segment.c nilfs2: fix null pointer dereference at nilfs_segctor_do_construct() 2020-06-10 19:14:17 -07:00
segment.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
sufile.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
sufile.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
super.c nilfs2: switch to ->free_inode() 2019-05-01 22:43:25 -04:00
sysfs.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
sysfs.h nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
the_nilfs.c nilfs2: convert to SPDX license tags 2018-09-04 16:45:02 -07:00
the_nilfs.h block: remove the error_sector argument to blkdev_issue_flush 2020-05-22 08:45:46 -06:00