CVE-2026-46272
Beschrijving NL
In de Linux kernel is de volgende kwetsbaarheid verholpen:
coresight: tmc-etr: Raceconditie tussen sysfs en perf-modus repareren
Wanneer u de perf- en sysfs-modus tegelijkertijd probeert uit te voeren, wordt de WARN_ON()
in tmc_etr_enable_hw() wordt soms geactiveerd:
WAARSCHUWING: CPU: 42 PID: 3911571 bij drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc]
[..knip..]
Oproepspoor:
tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P)
tmc_enable_etr_sin k+0x11c/0x250 [coresight_tmc] (L)
tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc]
coresight_enable_path+0x1c8/0x218 [coresight]
coresight_enable_sysfs+0xa4/0x228 [coresight]
enable_source_store+0x58/0xa8 [coresight]
dev_attr_store+0x20/0x40
sysfs_kf_write+0x4c/0x68
kernfs_fop_write_iter+0x120/0x1b8
vfs_write+0x2c8/0x388
ksys_write+0x74/0x108
__arm64_sys_write+0x24/0x38
el0_svc_common.constprop.0+0x64/0x148
do_el0_svc+0x24/0x38
el0_svc+0x3c/0x130
el 0t_64_sync_handler+0xc8/0xd0
el0t_64_sync+0x1ac/0x1b0
---[ eindspoor 0000000000000000 ]---
Aangezien de inschakeling van sysfs-modus is onderverdeeld in twee kritieke regio's,
een voor sysfs-buffertoewijzing en een andere voor hardware-enablement, het is
mogelijk om te racen met de perf-modus. Los dit op door dubbel te controleren of
de perf-modus is gebruikt voordat de hardware in sysfs-modus werd ingeschakeld. modus:
[sysfs-modus] [perf-modus]
tmc_etr_get_sysfs_buffer()
spin_lock(&drvdata->spinlock)
[sysfs-buffertoewijzing]
spin_unlock(&drvdata->spinlock)
spin_lock(&drvdata->spinlock)
tmc_etr_enable_hw()
drvdata->etr_buf = etr_perf->etr_buf
spin_unlock(&drvdata->spinlock)
s pin_lock(&drvdata->spinlock)
tmc_etr_enable_hw()
WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf geïnitialiseerd op
de perf side
spin_unlock(&drvdata->spinlock)
Met deze oplossing behouden we de cheque voor CS_mode_PERF in get_etr_sysfs_buf. Dit zorgt ervoor dat we controleren of de perf-modus al actief is voordat we
eigenlijk de buffer toe te wijzen. Dan kunnen we de tijd van
toewijzen/vrijmaken van de sysfs-buffer indien race met de perf-modus.
Origineel (Engels) tonen
In the Linux kernel, the following vulnerability has been resolved:
coresight: tmc-etr: Fix race condition between sysfs and perf mode
When trying to run perf and sysfs mode simultaneously, the WARN_ON()
in tmc_etr_enable_hw() is triggered sometimes:
WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc]
[..snip..]
Call trace:
tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P)
tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L)
tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc]
coresight_enable_path+0x1c8/0x218 [coresight]
coresight_enable_sysfs+0xa4/0x228 [coresight]
enable_source_store+0x58/0xa8 [coresight]
dev_attr_store+0x20/0x40
sysfs_kf_write+0x4c/0x68
kernfs_fop_write_iter+0x120/0x1b8
vfs_write+0x2c8/0x388
ksys_write+0x74/0x108
__arm64_sys_write+0x24/0x38
el0_svc_common.constprop.0+0x64/0x148
do_el0_svc+0x24/0x38
el0_svc+0x3c/0x130
el0t_64_sync_handler+0xc8/0xd0
el0t_64_sync+0x1ac/0x1b0
---[ end trace 0000000000000000 ]---
Since the enablement of sysfs mode is separeted into two critical regions,
one for sysfs buffer allocation and another for hardware enablement, it's
possible to race with the perf mode. Fix this by double check whether
the perf mode's been used before enabling the hardware in sysfs mode.
mode:
[sysfs mode] [perf mode]
tmc_etr_get_sysfs_buffer()
spin_lock(&drvdata->spinlock)
[sysfs buffer allocation]
spin_unlock(&drvdata->spinlock)
spin_lock(&drvdata->spinlock)
tmc_etr_enable_hw()
drvdata->etr_buf = etr_perf->etr_buf
spin_unlock(&drvdata->spinlock)
spin_lock(&drvdata->spinlock)
tmc_etr_enable_hw()
WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at
the perf side
spin_unlock(&drvdata->spinlock)
With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf.
This ensures we verify whether the perf mode's already running before we
actually allocate the buffer. Then we can save the time of
allocating/freeing the sysfs buffer if race with the perf mode.