- Linux-stable-mirror - lists.linaro.org

[PATCH] x86/kexec: Add a sanity check on previous kernel's ima kexec buffer

by Harshit Mogalapalli

When the second-stage kernel is booted via kexec with a limiting command line such as "mem=<size>", the physical range that contains the carried over IMA measurement list may fall outside the truncated RAM leading to a kernel panic. BUG: unable to handle page fault for address: ffff97793ff47000 RIP: ima_restore_measurement_list+0xdc/0x45a #PF: error_code(0x0000) – not-present page Other architectures already validate the range with page_is_ram(), as done in commit: cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer against memory bounds") do a similar check on x86. Cc: stable(a)vger.kernel.org Fixes: b69a2afd5afc ("x86/kexec: Carry forward IMA measurement log on kexec") Reported-by: Paul Webb <paul.x.webb(a)oracle.com> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli(a)oracle.com> --- Have tested the kexec for x86 kernel with IMA_KEXEC enabled and the above patch works good. Paul initially reported this on 6.12 kernel but I was able to reproduce this on 6.18, so I tried replicating how this was fixed in drivers/of/kexec.c --- arch/x86/kernel/setup.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 1b2edd07a3e1..fcef197d180e 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -439,9 +439,23 @@ int __init ima_free_kexec_buffer(void) int __init ima_get_kexec_buffer(void **addr, size_t *size) { + unsigned long start_pfn, end_pfn; + if (!ima_kexec_buffer_size) return -ENOENT; + /* + * Calculate the PFNs for the buffer and ensure + * they are with in addressable memory. + */ + start_pfn = PFN_DOWN(ima_kexec_buffer_phys); + end_pfn = PFN_DOWN(ima_kexec_buffer_phys + ima_kexec_buffer_size - 1); + if (!pfn_range_is_mapped(start_pfn, end_pfn)) { + pr_warn("IMA buffer at 0x%llx, size = 0x%zx beyond memory\n", + ima_kexec_buffer_phys, ima_kexec_buffer_size); + return -EINVAL; + } + *addr = __va(ima_kexec_buffer_phys); *size = ima_kexec_buffer_size; -- 2.50.1

2 days, 22 hours

6
7
0 0

[PATCH] cpufreq: amd_freq_sensitivity: Fix sensitivity clamping in amd_powersave_bias_target

by Thorsten Blum

The local variable 'sensitivity' was never clamped to 0 or POWERSAVE_BIAS_MAX because the return value of clamp() was not used. Fix this by assigning the clamped value back to 'sensitivity'. Cc: stable(a)vger.kernel.org Fixes: 9c5320c8ea8b ("cpufreq: AMD "frequency sensitivity feedback" powersave bias for ondemand governor") Signed-off-by: Thorsten Blum <thorsten.blum(a)linux.dev> --- drivers/cpufreq/amd_freq_sensitivity.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/cpufreq/amd_freq_sensitivity.c b/drivers/cpufreq/amd_freq_sensitivity.c index 13fed4b9e02b..713ccf24c97d 100644 --- a/drivers/cpufreq/amd_freq_sensitivity.c +++ b/drivers/cpufreq/amd_freq_sensitivity.c @@ -76,7 +76,7 @@ static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy, sensitivity = POWERSAVE_BIAS_MAX - (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference); - clamp(sensitivity, 0, POWERSAVE_BIAS_MAX); + sensitivity = clamp(sensitivity, 0, POWERSAVE_BIAS_MAX); /* this workload is not CPU bound, so choose a lower freq */ if (sensitivity < od_tuners->powersave_bias) { -- Thorsten Blum <thorsten.blum(a)linux.dev> GPG: 1D60 735E 8AEF 3BE4 73B6 9D84 7336 78FD 8DFE EAD4

2 days, 22 hours

2
1
0 0

[PATCH] iio: adc: PAC1934: Fix clamped value in pac1934_reg_snapshot

by Thorsten Blum

The local variable 'curr_energy' was never clamped to PAC_193X_MIN_POWER_ACC or PAC_193X_MAX_POWER_ACC because the return value of clamp() was not used. Fix this by assigning the clamped value back to 'curr_energy'. Cc: stable(a)vger.kernel.org Fixes: 0fb528c8255b ("iio: adc: adding support for PAC193x") Signed-off-by: Thorsten Blum <thorsten.blum(a)linux.dev> --- drivers/iio/adc/pac1934.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/pac1934.c b/drivers/iio/adc/pac1934.c index 48df16509260..256488d3936b 100644 --- a/drivers/iio/adc/pac1934.c +++ b/drivers/iio/adc/pac1934.c @@ -665,7 +665,8 @@ static int pac1934_reg_snapshot(struct pac1934_chip_info *info, /* add the power_acc field */ curr_energy += inc; - clamp(curr_energy, PAC_193X_MIN_POWER_ACC, PAC_193X_MAX_POWER_ACC); + curr_energy = clamp(curr_energy, PAC_193X_MIN_POWER_ACC, + PAC_193X_MAX_POWER_ACC); reg_data->energy_sec_acc[cnt] = curr_energy; } -- Thorsten Blum <thorsten.blum(a)linux.dev> GPG: 1D60 735E 8AEF 3BE4 73B6 9D84 7336 78FD 8DFE EAD4

2 days, 23 hours

2
1
0 0

[PATCH] fbdev/pxafb: Fix multiple clamped values in pxafb_adjust_timing

by Thorsten Blum

The variables were never clamped because the return value of clamp_val() was not used. Fix this by assigning the clamped values, and use clamp() instead of clamp_val(). Cc: stable(a)vger.kernel.org Fixes: 3f16ff608a75 ("[ARM] pxafb: cleanup of the timing checking code") Signed-off-by: Thorsten Blum <thorsten.blum(a)linux.dev> --- drivers/video/fbdev/pxafb.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/video/fbdev/pxafb.c b/drivers/video/fbdev/pxafb.c index b96a8a96bce8..e418eee825fb 100644 --- a/drivers/video/fbdev/pxafb.c +++ b/drivers/video/fbdev/pxafb.c @@ -419,12 +419,12 @@ static int pxafb_adjust_timing(struct pxafb_info *fbi, var->yres = max_t(int, var->yres, MIN_YRES); if (!(fbi->lccr0 & LCCR0_LCDT)) { - clamp_val(var->hsync_len, 1, 64); - clamp_val(var->vsync_len, 1, 64); - clamp_val(var->left_margin, 1, 255); - clamp_val(var->right_margin, 1, 255); - clamp_val(var->upper_margin, 1, 255); - clamp_val(var->lower_margin, 1, 255); + var->hsync_len = clamp(var->hsync_len, 1, 64); + var->vsync_len = clamp(var->vsync_len, 1, 64); + var->left_margin = clamp(var->left_margin, 1, 255); + var->right_margin = clamp(var->right_margin, 1, 255); + var->upper_margin = clamp(var->upper_margin, 1, 255); + var->lower_margin = clamp(var->lower_margin, 1, 255); } /* make sure each line is aligned on word boundary */ -- Thorsten Blum <thorsten.blum(a)linux.dev> GPG: 1D60 735E 8AEF 3BE4 73B6 9D84 7336 78FD 8DFE EAD4

2 days, 23 hours

1
0
0 0

[PATCH v6 0/9] Error recovery for vfio-pci devices on s390x

by Farhan Ali

Hi, This Linux kernel patch series introduces support for error recovery for passthrough PCI devices on System Z (s390x). Background ---------- For PCI devices on s390x an operating system receives platform specific error events from firmware rather than through AER.Today for passthrough/userspace devices, we don't attempt any error recovery and ignore any error events for the devices. The passthrough/userspace devices are managed by the vfio-pci driver. The driver does register error handling callbacks (error_detected), and on an error trigger an eventfd to userspace. But we need a mechanism to notify userspace (QEMU/guest/userspace drivers) about the error event. Proposal -------- We can expose this error information (currently only the PCI Error Code) via a device feature. Userspace can then obtain the error information via VFIO_DEVICE_FEATURE ioctl and take appropriate actions such as driving a device reset. This is how a typical flow for passthrough devices to a VM would work: For passthrough devices to a VM, the driver bound to the device on the host is vfio-pci. vfio-pci driver does support the error_detected() callback (vfio_pci_core_aer_err_detected()), and on an PCI error s390x recovery code on the host will call the vfio-pci error_detected() callback. The vfio-pci error_detected() callback will notify userspace/QEMU via an eventfd, and return PCI_ERS_RESULT_CAN_RECOVER. At this point the s390x error recovery on the host will skip any further action(see patch 6) and let userspace drive the error recovery. Once userspace/QEMU is notified, it then injects this error into the VM so device drivers in the VM can take recovery actions. For example for a passthrough NVMe device, the VM's OS NVMe driver will access the device. At this point the VM's NVMe driver's error_detected() will drive the recovery by returning PCI_ERS_RESULT_NEED_RESET, and the s390x error recovery in the VM's OS will try to do a reset. Resets are privileged operations and so the VM will need intervention from QEMU to perform the reset. QEMU will invoke the VFIO_DEVICE_RESET ioctl to now notify the host that the VM is requesting a reset of the device. The vfio-pci driver on the host will then perform the reset on the device to recover it. Thanks Farhan ChangeLog --------- v5 series https://lore.kernel.org/all/20251113183502.2388-1-alifm@linux.ibm.com/ v5 -> v6 - Rebase on 6.18 + Lukas's PCI: Universal error recoverability of devices series (https://lore.kernel.org/all/cover.1763483367.git.lukas@wunner.de/) - Re-work config space accessibility check to pci_dev_save_and_disable() (patch 3). This avoids saving the config space, in the reset path, if the device's config space is corrupted or inaccessible. v4 series https://lore.kernel.org/all/20250924171628.826-1-alifm@linux.ibm.com/ v4 -> v5 - Rebase on 6.18-rc5 - Move bug fixes to the beginning of the series (patch 1 and 2). These patches were posted as a separate fixes series https://lore.kernel.org/all/a14936ac-47d6-461b-816f-0fd66f869b0f@linux.ibm.… - Add matching pci_put_dev() for pci_get_slot() (patch 6). v3 series https://lore.kernel.org/all/20250911183307.1910-1-alifm@linux.ibm.com/ v3 -> v4 - Remove warn messages for each PCI capability not restored (patch 1) - Check PCI_COMMAND and PCI_STATUS register for error value instead of device id (patch 1) - Fix kernel crash in patch 3 - Added reviewed by tags - Address comments from Niklas's (patches 4, 5, 7) - Fix compilation error non s390x system (patch 8) - Explicitly align struct vfio_device_feature_zpci_err (patch 8) v2 series https://lore.kernel.org/all/20250825171226.1602-1-alifm@linux.ibm.com/ v2 -> v3 - Patch 1 avoids saving any config space state if the device is in error (suggested by Alex) - Patch 2 adds additional check only for FLR reset to try other function reset method (suggested by Alex). - Patch 3 fixes a bug in s390 for resetting PCI devices with multiple functions. Creates a new flag pci_slot to allow per function slot. - Patch 4 fixes a bug in s390 for resource to bus address translation. - Rebase on 6.17-rc5 v1 series https://lore.kernel.org/all/20250813170821.1115-1-alifm@linux.ibm.com/ v1 - > v2 - Patches 1 and 2 adds some additional checks for FLR/PM reset to try other function reset method (suggested by Alex). - Patch 3 fixes a bug in s390 for resetting PCI devices with multiple functions. - Patch 7 adds a new device feature for zPCI devices for the VFIO_DEVICE_FEATURE ioctl. The ioctl is used by userspace to retriece any PCI error information for the device (suggested by Alex). - Patch 8 adds a reset_done() callback for the vfio-pci driver, to restore the state of the device after a reset. - Patch 9 removes the pcie check for triggering VFIO_PCI_ERR_IRQ_INDEX. Farhan Ali (9): PCI: Allow per function PCI slots s390/pci: Add architecture specific resource/bus address translation PCI: Avoid saving config space state if inaccessible PCI: Add additional checks for flr reset s390/pci: Update the logic for detecting passthrough device s390/pci: Store PCI error information for passthrough devices vfio-pci/zdev: Add a device feature for error information vfio: Add a reset_done callback for vfio-pci driver vfio: Remove the pcie check for VFIO_PCI_ERR_IRQ_INDEX arch/s390/include/asm/pci.h | 29 ++++++++ arch/s390/pci/pci.c | 75 +++++++++++++++++++++ arch/s390/pci/pci_event.c | 107 +++++++++++++++++------------- drivers/pci/host-bridge.c | 4 +- drivers/pci/pci.c | 19 +++++- drivers/pci/slot.c | 25 ++++++- drivers/vfio/pci/vfio_pci_core.c | 20 ++++-- drivers/vfio/pci/vfio_pci_intrs.c | 3 +- drivers/vfio/pci/vfio_pci_priv.h | 9 +++ drivers/vfio/pci/vfio_pci_zdev.c | 45 ++++++++++++- include/linux/pci.h | 1 + include/uapi/linux/vfio.h | 15 +++++ 12 files changed, 291 insertions(+), 61 deletions(-) -- 2.43.0

2 days, 23 hours

3
12
0 0

[PATCH] bus: fsl-mc: fix use-after-free in driver_override_show()

by Gui-Dong Han

The driver_override_show() function reads the driver_override string without holding the device_lock. However, driver_override_store() uses driver_set_override(), which modifies and frees the string while holding the device_lock. This can result in a concurrent use-after-free if the string is freed by the store function while being read by the show function. Fix this by holding the device_lock around the read operation. Fixes: 1f86a00c1159 ("bus/fsl-mc: add support for 'driver_override' in the mc-bus") Cc: stable(a)vger.kernel.org Signed-off-by: Gui-Dong Han <hanguidong02(a)gmail.com> --- I verified this with a stress test that continuously writes/reads the attribute. It triggered KASAN and leaked bytes like a0 f4 81 9f a3 ff ff (likely kernel pointers). Since driver_override is world-readable (0644), this allows unprivileged users to leak kernel pointers and bypass KASLR. Similar races were fixed in other buses (e.g., commits 9561475db680 and 91d44c1afc61). Currently, 9 of 11 buses handle this correctly; this patch fixes one of the remaining two. --- drivers/bus/fsl-mc/fsl-mc-bus.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c index 25845c04e562..a97baf2cbcdd 100644 --- a/drivers/bus/fsl-mc/fsl-mc-bus.c +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c @@ -202,8 +202,12 @@ static ssize_t driver_override_show(struct device *dev, struct device_attribute *attr, char *buf) { struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); + ssize_t len; - return sysfs_emit(buf, "%s\n", mc_dev->driver_override); + device_lock(dev); + len = sysfs_emit(buf, "%s\n", mc_dev->driver_override); + device_unlock(dev); + return len; } static DEVICE_ATTR_RW(driver_override); -- 2.43.0

3 days

1
0
0 0

LDI Show 2025 Data

by Megan Castillo

Hi, Ahead of LDI Show 2025 (Dec 3–9, Las Vegas), we have access to a verified audience of 16,594 and a strong exhibitor roster of 312 top suppliers and vendors. This includes lighting & audio equipment manufacturers, staging/rigging vendors, media-server / projection / video providers, production houses, rental companies, sound & lighting engineers, stage managers , other live-event technology stakeholders and many. If interested, reply “Send Pricing” to receive the details. Best regards, Megan Castillio Head of Client Relations To opt-out, reply “Not Interested”.

3 days

1
0
0 0

+ ocfs2-fix-kernel-bug-in-ocfs2_find_victim_chain.patch added to mm-nonmm-unstable branch

by Andrew Morton

The patch titled Subject: ocfs2: fix kernel BUG in ocfs2_find_victim_chain has been added to the -mm mm-nonmm-unstable branch. Its filename is ocfs2-fix-kernel-bug-in-ocfs2_find_victim_chain.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Prithvi Tambewagh <activprithvi(a)gmail.com> Subject: ocfs2: fix kernel BUG in ocfs2_find_victim_chain Date: Mon, 1 Dec 2025 18:37:11 +0530 syzbot reported a kernel BUG in ocfs2_find_victim_chain() because the `cl_next_free_rec` field of the allocation chain list (next free slot in the chain list) is 0, triggring the BUG_ON(!cl->cl_next_free_rec) condition in ocfs2_find_victim_chain() and panicking the kernel. To fix this, an if condition is introduced in ocfs2_claim_suballoc_bits(), just before calling ocfs2_find_victim_chain(), the code block in it being executed when either of the following conditions is true: 1. `cl_next_free_rec` is equal to 0, indicating that there are no free chains in the allocation chain list 2. `cl_next_free_rec` is greater than `cl_count` (the total number of chains in the allocation chain list) Either of them being true is indicative of the fact that there are no chains left for usage. This is addressed using ocfs2_error(), which prints the error log for debugging purposes, rather than panicking the kernel. Link: https://lkml.kernel.org/r/20251201130711.143900-1-activprithvi@gmail.com Signed-off-by: Prithvi Tambewagh <activprithvi(a)gmail.com> Reported-by: syzbot+96d38c6e1655c1420a72(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=96d38c6e1655c1420a72 Tested-by: syzbot+96d38c6e1655c1420a72(a)syzkaller.appspotmail.com Reviewed-by: Joseph Qi <joseph.qi(a)linux.alibaba.com> Cc: Mark Fasheh <mark(a)fasheh.com> Cc: Joel Becker <jlbec(a)evilplan.org> Cc: Junxiao Bi <junxiao.bi(a)oracle.com> Cc: Changwei Ge <gechangwei(a)live.cn> Cc: Jun Piao <piaojun(a)huawei.com> Cc: Heming Zhao <heming.zhao(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/ocfs2/suballoc.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/fs/ocfs2/suballoc.c~ocfs2-fix-kernel-bug-in-ocfs2_find_victim_chain +++ a/fs/ocfs2/suballoc.c @@ -1993,6 +1993,16 @@ static int ocfs2_claim_suballoc_bits(str } cl = (struct ocfs2_chain_list *) &fe->id2.i_chain; + if (!le16_to_cpu(cl->cl_next_free_rec) || + le16_to_cpu(cl->cl_next_free_rec) > le16_to_cpu(cl->cl_count)) { + status = ocfs2_error(ac->ac_inode->i_sb, + "Chain allocator dinode %llu has invalid next " + "free chain record %u, but only %u total\n", + (unsigned long long)le64_to_cpu(fe->i_blkno), + le16_to_cpu(cl->cl_next_free_rec), + le16_to_cpu(cl->cl_count)); + goto bail; + } victim = ocfs2_find_victim_chain(cl); ac->ac_chain = victim; _ Patches currently in -mm which might be from activprithvi(a)gmail.com are ocfs2-fix-kernel-bug-in-ocfs2_find_victim_chain.patch

3 days, 1 hour

1
0
0 0

[PATCH] KVM: x86/pmu: Do not accidentally create BTS events

by Fernand Sieber

From: Jan H. Schönherr <jschoenh(a)amazon.de> It is possible to degrade host performance by manipulating performance counters from a VM and tricking the host hypervisor to enable branch tracing. When the guest programs a CPU to track branch instructions and deliver an interrupt after exactly one branch instruction, the value one is handled by the host KVM/perf subsystems and treated incorrectly as a special value to enable the branch trace store (BTS) subsystem. It should not be possible to enable BTS from a guest. When BTS is enabled, it leads to general host performance degradation to both VMs and host. Perf considers the combination of PERF_COUNT_HW_BRANCH_INSTRUCTIONS with a sample_period of 1 a special case and handles this as a BTS event (see intel_pmu_has_bts_period()) -- a deviation from the usual semantic, where the sample_period represents the amount of branch instructions to encounter before the overflow handler is invoked. Nothing prevents a guest from programming its vPMU with the above settings (count branch, interrupt after one branch), which causes KVM to erroneously instruct perf to create a BTS event within pmc_reprogram_counter(), which does not have the desired semantics. The guest could also do more benign actions and request an interrupt after a more reasonable number of branch instructions via its vPMU. In that case counting works initially. However, KVM occasionally pauses and resumes the created performance counters. If the remaining amount of branch instructions until interrupt has reached 1 exactly, pmc_resume_counter() fails to resume the counter and a BTS event is created instead with its incorrect semantics. Fix this behavior by not passing the special value "1" as sample_period to perf. Instead, perform the same quirk that happens later in x86_perf_event_set_period() anyway, when the performance counter is transferred to the actual PMU: bump the sample_period to 2. Testing: From guest: `./wrmsr -p 12 0x186 0x1100c4` `./wrmsr -p 12 0xc1 0xffffffffffff` `./wrmsr -p 12 0x186 0x5100c4` This sequence sets up branch instruction counting, initializes the counter to overflow after one event (0xffffffffffff), and then enables edge detection (bit 18) for branch events. ./wrmsr -p 12 0x186 0x1100c4 Writes to IA32_PERFEVTSEL0 (0x186) Value 0x1100c4 breaks down as: Event = 0xC4 (Branch instructions) Bits 16-17: 0x1 (User mode only) Bit 22: 1 (Enable counter) ./wrmsr -p 12 0xc1 0xffffffffffff Writes to IA32_PMC0 (0xC1) Sets counter to maximum value (0xffffffffffff) This effectively sets up the counter to overflow on the next branch ./wrmsr -p 12 0x186 0x5100c4 Updates IA32_PERFEVTSEL0 again Similar to first command but adds bit 18 (0x4 to 0x5) Enables edge detection (bit 18) These MSR writes are trapped by the hypervisor in KVM and forwarded to the perf subsystem to create corresponding monitoring events. It is possible to repro this problem in a more realistic guest scenario: `perf record -e branches:u -c 2 -a &` `perf record -e branches:u -c 2 -a &` This presumably triggers the issue by KVM pausing and resuming the performance counter at the wrong moment, when its value is about to overflow. Signed-off-by: Jan H. Schönherr <jschoenh(a)amazon.de> Signed-off-by: Fernand Sieber <sieberf(a)amazon.com> Reviewed-by: David Woodhouse <dwmw(a)amazon.co.uk> Reviewed-by: Hendrik Borghorst <hborghor(a)amazon.de> Link: https://lore.kernel.org/r/20251124100220.238177-1-sieberf@amazon.com --- arch/x86/kvm/pmu.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 487ad19a236e..547512028e24 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -225,6 +225,19 @@ static u64 get_sample_period(struct kvm_pmc *pmc, u64 counter_value) { u64 sample_period = (-counter_value) & pmc_bitmask(pmc); + /* + * A sample_period of 1 might get mistaken by perf for a BTS event, see + * intel_pmu_has_bts_period(). This would prevent re-arming the counter + * via pmc_resume_counter(), followed by the accidental creation of an + * actual BTS event, which we do not want. + * + * Avoid this by bumping the sampling period. Note, that we do not lose + * any precision, because the same quirk happens later anyway (for + * different reasons) in x86_perf_event_set_period(). + */ + if (sample_period == 1) + sample_period = 2; + if (!sample_period) sample_period = pmc_bitmask(pmc) + 1; return sample_period; -- 2.43.0 Amazon Development Centre (South Africa) (Proprietary) Limited 29 Gogosoa Street, Observatory, Cape Town, Western Cape, 7925, South Africa Registration Number: 2004 / 034463 / 07

3 days, 1 hour

5
7
0 0

FAILED: patch "[PATCH] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x eb76d0f5553575599561010f24c277cc5b31d003 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025120119-quake-universal-d896@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From eb76d0f5553575599561010f24c277cc5b31d003 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann <tzimmermann(a)suse.de> Date: Wed, 5 Nov 2025 17:14:49 +0100 Subject: [PATCH] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB access in fbcon_remap_all(). Without holding the console lock the call races with switching outputs. VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon function uses struct fb_info.node, which is set by register_framebuffer(). As the fb-helper code currently sets up VGA switcheroo before registering the framebuffer, the value of node is -1 and therefore not a legal value. For example, fbcon uses the value within set_con2fb_map() [1] as an index into an array. Moving vga_switcheroo_client_fb_set() after register_framebuffer() can result in VGA switching that does not switch fbcon correctly. Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(), which already holds the console lock. Fbdev calls fbcon_fb_registered() from within register_framebuffer(). Serializes the helper with VGA switcheroo's call to fbcon_remap_all(). Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info as parameter, it really only needs the contained fbcon state. Moving the call to fbcon initialization is therefore cleaner than before. Only amdgpu, i915, nouveau and radeon support vga_switcheroo. For all other drivers, this change does nothing. Signed-off-by: Thomas Zimmermann <tzimmermann(a)suse.de> Link: https://elixir.bootlin.com/linux/v6.17/source/drivers/video/fbdev/core/fbco… # [1] Fixes: 6a9ee8af344e ("vga_switcheroo: initial implementation (v15)") Acked-by: Javier Martinez Canillas <javierm(a)redhat.com> Acked-by: Alex Deucher <alexander.deucher(a)amd.com> Cc: dri-devel(a)lists.freedesktop.org Cc: nouveau(a)lists.freedesktop.org Cc: amd-gfx(a)lists.freedesktop.org Cc: linux-fbdev(a)vger.kernel.org Cc: <stable(a)vger.kernel.org> # v2.6.34+ Link: https://patch.msgid.link/20251105161549.98836-1-tzimmermann@suse.de diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 11a5b60cb9ce..0b3ee008523d 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -31,9 +31,7 @@ #include <linux/console.h> #include <linux/export.h> -#include <linux/pci.h> #include <linux/sysrq.h> -#include <linux/vga_switcheroo.h> #include <drm/drm_atomic.h> #include <drm/drm_drv.h> @@ -566,11 +564,6 @@ EXPORT_SYMBOL(drm_fb_helper_release_info); */ void drm_fb_helper_unregister_info(struct drm_fb_helper *fb_helper) { - struct fb_info *info = fb_helper->info; - struct device *dev = info->device; - - if (dev_is_pci(dev)) - vga_switcheroo_client_fb_set(to_pci_dev(dev), NULL); unregister_framebuffer(fb_helper->info); } EXPORT_SYMBOL(drm_fb_helper_unregister_info); @@ -1632,7 +1625,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper) struct drm_client_dev *client = &fb_helper->client; struct drm_device *dev = fb_helper->dev; struct drm_fb_helper_surface_size sizes; - struct fb_info *info; int ret; if (drm_WARN_ON(dev, !dev->driver->fbdev_probe)) @@ -1653,12 +1645,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper) strcpy(fb_helper->fb->comm, "[fbcon]"); - info = fb_helper->info; - - /* Set the fb info for vgaswitcheroo clients. Does nothing otherwise. */ - if (dev_is_pci(info->device)) - vga_switcheroo_client_fb_set(to_pci_dev(info->device), info); - return 0; } diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 9bd3c3814b5c..e7e07eb2142e 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -66,6 +66,7 @@ #include <linux/string.h> #include <linux/kd.h> #include <linux/panic.h> +#include <linux/pci.h> #include <linux/printk.h> #include <linux/slab.h> #include <linux/fb.h> @@ -78,6 +79,7 @@ #include <linux/interrupt.h> #include <linux/crc32.h> /* For counting font checksums */ #include <linux/uaccess.h> +#include <linux/vga_switcheroo.h> #include <asm/irq.h> #include "fbcon.h" @@ -2899,6 +2901,9 @@ void fbcon_fb_unregistered(struct fb_info *info) console_lock(); + if (info->device && dev_is_pci(info->device)) + vga_switcheroo_client_fb_set(to_pci_dev(info->device), NULL); + fbcon_registered_fb[info->node] = NULL; fbcon_num_registered_fb--; @@ -3032,6 +3037,10 @@ static int do_fb_registered(struct fb_info *info) } } + /* Set the fb info for vga_switcheroo clients. Does nothing otherwise. */ + if (info->device && dev_is_pci(info->device)) + vga_switcheroo_client_fb_set(to_pci_dev(info->device), info); + return ret; }

3 days, 1 hour

4
3
0 0

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-stable-mirror