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Date:   Wed, 22 Feb 2023 13:12:08 +0000
From:   Tudor Ambarus <tudor.ambarus@...aro.org>
To:     tytso@....edu, darrick.wong@...cle.com, djwong@...nel.org,
        adilger.kernel@...ger.ca
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        joneslee@...gle.com, Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH 0/3] ext4: fsmap: Improve key validation

Fix the bug reported at:
https://syzkaller.appspot.com/bug?id=79d5768e9bfe362911ac1a5057a36fc6b5c30002

Darrick J. Wong proposed a similar patch to address the same bug at:
https://lore.kernel.org/linux-ext4/3e125c64-da56-2a2b-1a20-fdcc5a0d3014@linaro.org/

I think my version of the patch is better. It clearly indicates that
lower out of bounds requests are ignored. The high key should be greater
than the first data block for the ext4_getfsmap_datadev() handler,
otherwise there's no data to return, thus we exit early and ignore the
request. Darrick indirectly implied the same thing, but missed the case
where the high_key->fmr_phisical is equal to the first data block.

After the fix you'll find another patch that consolidates the validation
of the user provided data. Instead of having the checks scattered among
the fsmap representations, gather the code in a single method and do the
checks directly on the data received from user.
Similar patch can be done for xfs fsmap, but I'll wait for some
feedback first.

Tested the changes with kvm-xfstests: ext4/{027, 028, 029}, all passed,
output below.

Cheers,
ta

-------------------- Summary report
KERNEL:    kernel 6.2.0-rc8-xfstests-00003-gc34cc283e325 #13 SMP PREEMPT_DYNAMIC Wed Feb 22 12:35:39 UTC 2023 x86_64
CMDLINE:   ext4/027
CPUS:      2
MEM:       1975.3

ext4/4k: 1 tests, 1 seconds
  ext4/027     Pass     1s
ext4/1k: 1 tests, 1 seconds
  ext4/027     Pass     1s
ext4/ext3: 1 tests, 2 seconds
  ext4/027     Pass     1s
ext4/encrypt: 1 tests, 1 seconds
  ext4/027     Pass     0s
ext4/nojournal: 1 tests, 1 seconds
  ext4/027     Pass     1s
ext4/ext3conv: 1 tests, 1 seconds
  ext4/027     Pass     0s
ext4/adv: 1 tests, 1 seconds
  ext4/027     Pass     1s
ext4/dioread_nolock: 1 tests, 1 seconds
  ext4/027     Pass     1s
ext4/data_journal: 1 tests, 1 seconds
  ext4/027     Pass     0s
ext4/bigalloc: 1 tests, 1 seconds
  ext4/027     Pass     0s
ext4/bigalloc_1k: 1 tests, 1 seconds
  ext4/027     Pass     0s
Totals: 11 tests, 0 skipped, 0 failures, 0 errors, 6s

FSTESTVER: blktests 4e07b0c (Fri, 15 Jul 2022 14:40:03 +0900)
FSTESTVER: fio  fio-3.31 (Tue, 9 Aug 2022 14:41:25 -0600)
FSTESTVER: fsverity v1.5 (Sun, 6 Feb 2022 10:59:13 -0800)
FSTESTVER: ima-evm-utils v1.3.2 (Wed, 28 Oct 2020 13:18:08 -0400)
FSTESTVER: nvme-cli v1.16 (Thu, 11 Nov 2021 13:09:06 -0800)
FSTESTVER: quota  v4.05-43-gd2256ac (Fri, 17 Sep 2021 14:04:16 +0200)
FSTESTVER: util-linux v2.38.1 (Thu, 4 Aug 2022 11:06:21 +0200)
FSTESTVER: xfsprogs v5.19.0 (Fri, 12 Aug 2022 13:45:01 -0500)
FSTESTVER: xfstests v2022.08.21-8-g289f50f8 (Sun, 21 Aug 2022 15:21:34 -0400)
FSTESTVER: xfstests-bld bb566bcf (Wed, 24 Aug 2022 23:07:24 -0400)
FSTESTVER: zz_build-distro bullseye
FSTESTCFG: all
FSTESTSET: ext4/027
FSTESTOPT: aex
[   59.553199] ACPI: PM: Preparing to enter system sleep state S5
[   59.557660] reboot: Power down

-------------------- Summary report
KERNEL:    kernel 6.2.0-rc8-xfstests-00003-gc34cc283e325 #13 SMP PREEMPT_DYNAMIC Wed Feb 22 12:35:39 UTC 2023 x86_64
CMDLINE:   ext4/028
CPUS:      2
MEM:       1975.31

ext4/4k: 1 tests, 1 seconds
  ext4/028     Pass     1s
ext4/1k: 1 tests, 3 seconds
  ext4/028     Pass     3s
ext4/ext3: 1 tests, 1 skipped, 1 seconds
  ext4/028     Skipped  1s
ext4/encrypt: 0 tests, 0 seconds
ext4/nojournal: 1 tests, 4 seconds
  ext4/028     Pass     4s
ext4/ext3conv: 1 tests, 5 seconds
  ext4/028     Pass     4s
ext4/adv: 1 tests, 4 seconds
  ext4/028     Pass     4s
ext4/dioread_nolock: 1 tests, 1 seconds
  ext4/028     Pass     1s
ext4/data_journal: 1 tests, 1 seconds
  ext4/028     Pass     1s
ext4/bigalloc: 1 tests, 5 seconds
  ext4/028     Pass     5s
ext4/bigalloc_1k: 1 tests, 3 seconds
  ext4/028     Pass     2s
Totals: 10 tests, 1 skipped, 0 failures, 0 errors, 26s

FSTESTVER: blktests 4e07b0c (Fri, 15 Jul 2022 14:40:03 +0900)
FSTESTVER: fio  fio-3.31 (Tue, 9 Aug 2022 14:41:25 -0600)
FSTESTVER: fsverity v1.5 (Sun, 6 Feb 2022 10:59:13 -0800)
FSTESTVER: ima-evm-utils v1.3.2 (Wed, 28 Oct 2020 13:18:08 -0400)
FSTESTVER: nvme-cli v1.16 (Thu, 11 Nov 2021 13:09:06 -0800)
FSTESTVER: quota  v4.05-43-gd2256ac (Fri, 17 Sep 2021 14:04:16 +0200)
FSTESTVER: util-linux v2.38.1 (Thu, 4 Aug 2022 11:06:21 +0200)
FSTESTVER: xfsprogs v5.19.0 (Fri, 12 Aug 2022 13:45:01 -0500)
FSTESTVER: xfstests v2022.08.21-8-g289f50f8 (Sun, 21 Aug 2022 15:21:34 -0400)
FSTESTVER: xfstests-bld bb566bcf (Wed, 24 Aug 2022 23:07:24 -0400)
FSTESTVER: zz_build-distro bullseye
FSTESTCFG: all
FSTESTSET: ext4/028
FSTESTOPT: aex
[   76.557142] EXT4-fs (vdg): unmounting filesystem 3149a29d-9b44-4c17-82a6-c86addd7f1bb.
[   76.592295] ACPI: PM: Preparing to enter system sleep state S5
[   76.597019] reboot: Power down

-------------------- Summary report
KERNEL:    kernel 6.2.0-rc8-xfstests-00003-gc34cc283e325 #13 SMP PREEMPT_DYNAMIC Wed Feb 22 12:35:39 UTC 2023 x86_64
CMDLINE:   -c logdev ext4/029
CPUS:      2
MEM:       1975.31

ext4/logdev: 1 tests, 1 seconds
  ext4/029     Pass     1s
Totals: 1 tests, 0 skipped, 0 failures, 0 errors, 1s

FSTESTVER: blktests 4e07b0c (Fri, 15 Jul 2022 14:40:03 +0900)
FSTESTVER: fio  fio-3.31 (Tue, 9 Aug 2022 14:41:25 -0600)
FSTESTVER: fsverity v1.5 (Sun, 6 Feb 2022 10:59:13 -0800)
FSTESTVER: ima-evm-utils v1.3.2 (Wed, 28 Oct 2020 13:18:08 -0400)
FSTESTVER: nvme-cli v1.16 (Thu, 11 Nov 2021 13:09:06 -0800)
FSTESTVER: quota  v4.05-43-gd2256ac (Fri, 17 Sep 2021 14:04:16 +0200)
FSTESTVER: util-linux v2.38.1 (Thu, 4 Aug 2022 11:06:21 +0200)
FSTESTVER: xfsprogs v5.19.0 (Fri, 12 Aug 2022 13:45:01 -0500)
FSTESTVER: xfstests v2022.08.21-8-g289f50f8 (Sun, 21 Aug 2022 15:21:34 -0400)
FSTESTVER: xfstests-bld bb566bcf (Wed, 24 Aug 2022 23:07:24 -0400)
FSTESTVER: zz_build-distro bullseye
FSTESTCFG: logdev
FSTESTSET: ext4/029
FSTESTOPT: aex
[    8.217384] reboot: Power down

Tudor Ambarus (3):
  ext4: fsmap: Fix crash caused by poor key validation
  ext4: fsmap: Consolidate fsmap_head checks
  ext4: fsmap: Remove duplicated initialization

 fs/ext4/fsmap.c | 56 +++++++++++++++++++++++++++++++++++--------------
 fs/ext4/fsmap.h |  3 +++
 fs/ext4/ioctl.c | 17 +++------------
 3 files changed, 46 insertions(+), 30 deletions(-)

-- 
2.39.2.637.g21b0678d19-goog

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