CVE-2026-64164
Beschrijving NL
In de Linux kernel is de volgende kwetsbaarheid verholpen:
btrfs: tracepoints: fix slaap in atomaire context in btrfs_sync_file()
De trace event btrfs_sync_file() wordt aangeroepen in een atomaire context (alle trace
gebeurtenissen zijn) en de oproep naar dput(), die nodig is vanwege de oproep naar
dget_parent(), kan slapen en activeert een kernel splat. Dit kan worden gereproduceerd door de traceergebeurtenis in te schakelen en btrfs/056 uit te voeren
van fstests bijvoorbeeld. De in dmesg getoonde splat is de volgende:
[53.919] BUG: slaapfunctie aangeroepen vanuit ongeldige context op fs/dcache.c:970
[53.947] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 32773, naam: xfs_io
[53.988] preempt_count: 2, verwacht: 0
[53.967] RCU nestdiepte: 0, verwacht: 0
[53.943] Voorkeur uitgeschakeld bij:
[53.944] [] 0x0
[54.078] CPU: 0 UID: 0 PID: 32773 Comm: xfs_io Besmet: G W 7.1.0-rc1-btrfs-next-232+ #1 PREEMPT(vol)
[54.070] Besmet: [W]=WAARSCHUWEN
[54.071] Hardware naam: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
[54.072] Call Trace:
[54.074]
[54.076] dump_stack_lvl+0x56/0x80
[54.079] __might_resched.cold+0xd6/0x10f
[54.072] dput.part.0+0x24/0x110
[54.078] trace_event_raw_event_btrfs_sync_file+0x75/0x140 [btrfs]
[54.089] btrfs_sync_file+0x1ed/0x530 [btrfs]
[54.087] ? __handle_mm_fault+0x8ae/0xed0
[54.089] btrfs_do_write_iter+0x172/0x210 [btrfs]
[54.091] vfs_write+0x21f/0x450
[54.094] __x64_sys_pwrite64+0x8d/0xc0
[54.096] ? do_user_addr_fault+0x20c/0x670
[54.099] do_syscall_64+0x60/0xf20
[54.092] ? clear_bhb_loop+0x60/0xb0
[54.094] entry_SYSCALL_64_NA_hwframe+0x76/0x7e
Dus stop met het gebruik van dget_parent() en dput() en ga naar het oudergebit
rechtstreeks als gebit->d_ouder. Dit is ook wat ext4 doet in
zijn equivalente trace event ext4_sync_file_enter().
Origineel (Engels) tonen
In the Linux kernel, the following vulnerability has been resolved:
btrfs: tracepoints: fix sleep while in atomic context in btrfs_sync_file()
The trace event btrfs_sync_file() is called in an atomic context (all trace
events are) and its call to dput(), which is needed due to the call to
dget_parent(), can sleep, triggering a kernel splat.
This can be reproduced by enabling the trace event and running btrfs/056
from fstests for example. The splat shown in dmesg is the following:
[53.919] BUG: sleeping function called from invalid context at fs/dcache.c:970
[53.947] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 32773, name: xfs_io
[53.988] preempt_count: 2, expected: 0
[53.967] RCU nest depth: 0, expected: 0
[53.943] Preemption disabled at:
[53.944] [] 0x0
[54.078] CPU: 0 UID: 0 PID: 32773 Comm: xfs_io Tainted: G W 7.1.0-rc1-btrfs-next-232+ #1 PREEMPT(full)
[54.070] Tainted: [W]=WARN
[54.071] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
[54.072] Call Trace:
[54.074]
[54.076] dump_stack_lvl+0x56/0x80
[54.079] __might_resched.cold+0xd6/0x10f
[54.072] dput.part.0+0x24/0x110
[54.078] trace_event_raw_event_btrfs_sync_file+0x75/0x140 [btrfs]
[54.089] btrfs_sync_file+0x1ed/0x530 [btrfs]
[54.087] ? __handle_mm_fault+0x8ae/0xed0
[54.089] btrfs_do_write_iter+0x172/0x210 [btrfs]
[54.091] vfs_write+0x21f/0x450
[54.094] __x64_sys_pwrite64+0x8d/0xc0
[54.096] ? do_user_addr_fault+0x20c/0x670
[54.099] do_syscall_64+0x60/0xf20
[54.092] ? clear_bhb_loop+0x60/0xb0
[54.094] entry_SYSCALL_64_after_hwframe+0x76/0x7e
So stop using dget_parent() and dput() and access the parent dentry
directly as dentry->d_parent. This is also what ext4 is doing in
its equivalent trace event ext4_sync_file_enter().