CVE-2023-52897

[BUG] There are some reports from the mailing list that since v6.1 kernel, the WARNON() inside btrfsqgroupaccountextent() gets triggered during rescan:

WARNING: CPU: 3 PID: 6424 at fs/btrfs/qgroup.c:2756 btrfsqgroupaccountextents+0x1ae/0x260 [btrfs] CPU: 3 PID: 6424 Comm: snapperd Tainted: P OE 6.1.2-1-default #1 openSUSE Tumbleweed 05c7a1b1b61d5627475528f71f50444637b5aad7 RIP: 0010:btrfsqgroupaccountextents+0x1ae/0x260 [btrfs] Call Trace: <TASK> btrfscommittransaction+0x30c/0xb40 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] ? starttransaction+0xc3/0x5b0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] btrfsqgrouprescan+0x42/0xc0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] btrfsioctl+0x1ab9/0x25c0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] ? _rseqhandlenotifyresume+0xa9/0x4a0 ? mntputnoexpire+0x4a/0x240 ? _seccompfilter+0x319/0x4d0 _x64sysioctl+0x90/0xd0 dosyscall64+0x5b/0x80 ? syscallexittousermode+0x17/0x40 ? dosyscall64+0x67/0x80 entrySYSCALL64after_hwframe+0x63/0xcd RIP: 0033:0x7fd9b790d9bf </TASK>

[CAUSE] Since commit e15e9f43c7ca ("btrfs: introduce BTRFSQGROUPRUNTIMEFLAGNO_ACCOUNTING to skip qgroup accounting"), if our qgroup is already in inconsistent state, we will no longer do the time-consuming backref walk.

This can leave some qgroup records without a valid oldroots ulist. Normally this is fine, as btrfsqgroupaccountextents() would also skip those records if we have NO_ACCOUNTING flag set.

But there is a small window, if we have NOACCOUNTING flag set, and inserted some qgrouprecord without a old_roots ulist, but then the user triggered a qgroup rescan.

During btrfsqgrouprescan(), we firstly clear NO_ACCOUNTING flag, then commit current transaction.

And since we have a qgrouprecord with oldroots = NULL, we trigger the WARNON() during btrfsqgroupaccountextents().

[FIX] Unfortunately due to the introduction of NOACCOUNTING flag, the assumption that every qgrouprecord would have its old_roots populated is no longer correct.

Fix the false alerts and drop the WARN_ON().

Database specific

{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/52xxx/CVE-2023-52897.json",
    "cna_assigner": "Linux"
}

References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type: GIT
Repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events: Introduced

e15e9f43c7ca25603fcf4c20d44ec777726f1034

Fixed

bb2c2e62539f2b63c5e0beb51501d328260c7595

Fixed

75181406b4eafacc531ff2ee5fb032bd93317e2b

Affected versions

v6.*

v6.0

v6.1

v6.1-rc1

v6.1-rc2

v6.1-rc3

v6.1-rc4

v6.1-rc5

v6.1-rc6

v6.1-rc7

v6.1-rc8

v6.1.1

v6.1.2

v6.1.3

v6.1.4

v6.1.5

v6.1.6

v6.1.7

Database specific

vanir_signatures

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        "signature_type": "Function",
        "target": {
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        "target": {
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]

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-52897.json"

Git / github.com/gregkh/linux