2025-09-15 14:46:11
Linux
PUBLISHED
In the Linux kernel, the following vulnerability has been resolved:
btrfs: add handling for RAID1C23/DUP to btrfs_reduce_alloc_profile
Callers of `btrfs_reduce_alloc_profile` expect it to return exactly
one allocation profile flag, and failing to do so may ultimately
result in a WARN_ON and remount-ro when allocating new blocks, like
the below transaction abort on 6.1.
`btrfs_reduce_alloc_profile` has two ways of determining the profile,
first it checks if a conversion balance is currently running and
uses the profile were converting to. If no balance is currently
running, it returns the max-redundancy profile which at least one
block in the selected block group has.
This works by simply checking each known allocation profile bit in
redundancy order. However, `btrfs_reduce_alloc_profile` has not been
updated as new flags have been added - first with the `DUP` profile
and later with the RAID1C34 profiles.
Because of the way it checks, if we have blocks with different
profiles and at least one is known, that profile will be selected.
However, if none are known we may return a flag set with multiple
allocation profiles set.
This is currently only possible when a balance from one of the three
unhandled profiles to another of the unhandled profiles is canceled
after allocating at least one block using the new profile.
In that case, a transaction abort like the below will occur and the
filesystem will need to be mounted with -o skip_balance to get it
mounted rw again (but the balance cannot be resumed without a
similar abort).
[770.648] ------------[ cut here ]------------
[770.648] BTRFS: Transaction aborted (error -22)
[770.648] WARNING: CPU: 43 PID: 1159593 at fs/btrfs/extent-tree.c:4122 find_free_extent+0x1d94/0x1e00 [btrfs]
[770.648] CPU: 43 PID: 1159593 Comm: btrfs Tainted: G W 6.1.0-0.deb11.7-powerpc64le #1 Debian 6.1.20-2~bpo11+1a~test
[770.648] Hardware name: T2P9D01 REV 1.00 POWER9 0x4e1202 opal:skiboot-bc106a0 PowerNV
[770.648] NIP: c00800000f6784fc LR: c00800000f6784f8 CTR: c000000000d746c0
[770.648] REGS: c000200089afe9a0 TRAP: 0700 Tainted: G W (6.1.0-0.deb11.7-powerpc64le Debian 6.1.20-2~bpo11+1a~test)
[770.648] MSR: 9000000002029033