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Qu Wenruo 4a445b7b61 btrfs: don't merge pages into bio if their page offset is not contiguous [BUG] Zygo reported on latest development branch, he could hit ASSERT()/BUG_ON() caused crash when doing RAID5 recovery (intentionally corrupt one disk, and let btrfs to recover the data during read/scrub). And The following minimal reproducer can cause extent state leakage at rmmod time: mkfs.btrfs -f -d raid5 -m raid5 $dev1 $dev2 $dev3 -b 1G > /dev/null mount $dev1 $mnt fsstress -w -d $mnt -n 25 -s 1660807876 sync fssum -A -f -w /tmp/fssum.saved $mnt umount $mnt # Wipe the dev1 but keeps its super block xfs_io -c "pwrite -S 0x0 1m 1023m" $dev1 mount $dev1 $mnt fssum -r /tmp/fssum.saved $mnt > /dev/null umount $mnt rmmod btrfs This will lead to the following extent states leakage: BTRFS: state leak: start 499712 end 503807 state 5 in tree 1 refs 1 BTRFS: state leak: start 495616 end 499711 state 5 in tree 1 refs 1 BTRFS: state leak: start 491520 end 495615 state 5 in tree 1 refs 1 BTRFS: state leak: start 487424 end 491519 state 5 in tree 1 refs 1 BTRFS: state leak: start 483328 end 487423 state 5 in tree 1 refs 1 BTRFS: state leak: start 479232 end 483327 state 5 in tree 1 refs 1 BTRFS: state leak: start 475136 end 479231 state 5 in tree 1 refs 1 BTRFS: state leak: start 471040 end 475135 state 5 in tree 1 refs 1 [CAUSE] Since commit `7aa51232e2` ("btrfs: pass a btrfs_bio to btrfs_repair_one_sector"), we always use btrfs_bio->file_offset to determine the file offset of a page. But that usage assume that, one bio has all its page having a continuous page offsets. Unfortunately that's not true, btrfs only requires the logical bytenr contiguous when assembling its bios. From above script, we have one bio looks like this: fssum-27671 submit_one_bio: bio logical=217739264 len=36864 fssum-27671 submit_one_bio: r/i=5/261 page_offset=466944 <<< fssum-27671 submit_one_bio: r/i=5/261 page_offset=724992 <<< fssum-27671 submit_one_bio: r/i=5/261 page_offset=729088 fssum-27671 submit_one_bio: r/i=5/261 page_offset=733184 fssum-27671 submit_one_bio: r/i=5/261 page_offset=737280 fssum-27671 submit_one_bio: r/i=5/261 page_offset=741376 fssum-27671 submit_one_bio: r/i=5/261 page_offset=745472 fssum-27671 submit_one_bio: r/i=5/261 page_offset=749568 fssum-27671 submit_one_bio: r/i=5/261 page_offset=753664 Note that the 1st and the 2nd page has non-contiguous page offsets. This means, at repair time, we will have completely wrong file offset passed in: kworker/u32:2-19927 btrfs_repair_one_sector: r/i=5/261 page_off=729088 file_off=475136 bio_offset=8192 Since the file offset is incorrect, we latter incorrectly set the extent states, and no way to really release them. Thus later it causes the leakage. In fact, this can be even worse, since the file offset is incorrect, we can hit cases like the incorrect file offset belongs to a HOLE, and later cause btrfs_num_copies() to trigger error, finally hit BUG_ON()/ASSERT() later. [FIX] Add an extra condition in btrfs_bio_add_page() for uncompressed IO. Now we will have more strict requirement for bio pages: - They should all have the same mapping (the mapping check is already implied by the call chain) - Their logical bytenr should be adjacent This is the same as the old condition. - Their page_offset() (file offset) should be adjacent This is the new check. This would result a slightly increased amount of bios from btrfs (needs holes and inside the same stripe boundary to trigger). But this would greatly reduce the confusion, as it's pretty common to assume a btrfs bio would only contain continuous page cache. Later we may need extra cleanups, as we no longer needs to handle gaps between page offsets in endio functions. Currently this should be the minimal patch to fix commit `7aa51232e2` ("btrfs: pass a btrfs_bio to btrfs_repair_one_sector"). Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org> Fixes: `7aa51232e2` ("btrfs: pass a btrfs_bio to btrfs_repair_one_sector") Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>		2022-08-22 18:06:58 +02:00
arch	highmem: Make __kunmap_{local,atomic}() take const void pointer	2022-07-25 17:45:40 +02:00
block	block: fix missing blkcg_bio_issue_init	2022-07-14 10:54:49 -06:00
certs	certs: make system keyring depend on x509 parser	2022-07-24 12:53:55 -07:00
crypto	crypto: s390 - do not depend on CRYPTO_HW for SIMD implementations	2022-07-06 20:04:06 -07:00
Documentation	* Check for invalid flags to KVM_CAP_X86_USER_SPACE_MSR	2022-07-23 10:22:26 -07:00
drivers	- Make retbleed mitigations 64-bit only (32-bit will need a bit more	2022-07-24 09:40:17 -07:00
fs	btrfs: don't merge pages into bio if their page offset is not contiguous	2022-08-22 18:06:58 +02:00
include	block: add bdev_max_segments() helper	2022-07-25 17:45:41 +02:00
init	gcc-12: disable '-Warray-bounds' universally for now	2022-06-09 10:11:12 -07:00
ipc	ipc: Free mq_sysctls if ipc namespace creation failed	2022-06-22 17:47:41 -05:00
kernel	A single fix to correct a wrong BUG_ON() condition for deboosted tasks.	2022-07-24 09:50:53 -07:00
lib	ubsan: disable UBSAN_DIV_ZERO for clang	2022-07-14 15:45:26 -07:00
LICENSES	LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers	2021-12-16 14:33:10 +01:00
mm	highmem: Make __kunmap_{local,atomic}() take const void pointer	2022-07-25 17:45:40 +02:00
net	net/sched: cls_api: Fix flow action initialization	2022-07-20 10:54:27 +01:00
samples	Fixes and minor clean ups for tracing:	2022-07-12 16:17:40 -07:00
scripts	scripts/gdb: Fix gdb 'lx-symbols' command	2022-07-21 10:40:55 -07:00
security	lockdown: Fix kexec lockdown bypass with ima policy	2022-07-20 09:56:48 -07:00
sound	ASoC: Drop Rockchip BCLK management for v5.19	2022-07-15 12:31:07 +02:00
tools	* Check for invalid flags to KVM_CAP_X86_USER_SPACE_MSR	2022-07-23 10:22:26 -07:00
usr	Not a lot of material this cycle. Many singleton patches against various	2022-05-27 11:22:03 -07:00
virt	KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un\|}blocking	2022-06-09 10:52:20 -04:00
.clang-format	clang-format: Fix space after for_each macros	2022-05-20 19:27:16 +02:00
.cocciconfig
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	kbuild: split the second line of .mod into .usyms	2022-05-08 03:16:59 +09:00
.mailmap	cxl fixes for 5.19-rc6	2022-07-08 12:55:25 -07:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: mark ARM/PALM TREO SUPPORT orphan	2022-07-07 15:17:00 +02:00
Kbuild	kbuild: rename hostprogs-y/always to hostprogs/always-y	2020-02-04 01:53:07 +09:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Pin control fixes for the v5.19 kernel cycle:	2022-07-22 12:24:04 -07:00
Makefile	Linux 5.19-rc8	2022-07-24 13:26:27 -07:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.