user/sven/linux.git/kernel/resource.c, branch v6.11.3

resource: fix region_intersects() vs add_memory_driver_managed()

2024-10-10T10:03:54Z

commit b4afe4183ec77f230851ea139d91e5cf2644c68b upstream. On a system with CXL memory, the resource tree (/proc/iomem) related to CXL memory may look like something as follows. 490000000-50fffffff : CXL Window 0 490000000-50fffffff : region0 490000000-50fffffff : dax0.0 490000000-50fffffff : System RAM (kmem) Because drivers/dax/kmem.c calls add_memory_driver_managed() during onlining CXL memory, which makes "System RAM (kmem)" a descendant of "CXL Window X". This confuses region_intersects(), which expects all "System RAM" resources to be at the top level of iomem_resource. This can lead to bugs. For example, when the following command line is executed to write some memory in CXL memory range via /dev/mem, $ dd if=data of=/dev/mem bs=$((1 << 10)) seek=$((0x490000000 >> 10)) count=1 dd: error writing '/dev/mem': Bad address 1+0 records in 0+0 records out 0 bytes copied, 0.0283507 s, 0.0 kB/s the command fails as expected. However, the error code is wrong. It should be "Operation not permitted" instead of "Bad address". More seriously, the /dev/mem permission checking in devmem_is_allowed() passes incorrectly. Although the accessing is prevented later because ioremap() isn't allowed to map system RAM, it is a potential security issue. During command executing, the following warning is reported in the kernel log for calling ioremap() on system RAM. ioremap on RAM at 0x0000000490000000 - 0x0000000490000fff WARNING: CPU: 2 PID: 416 at arch/x86/mm/ioremap.c:216 __ioremap_caller.constprop.0+0x131/0x35d Call Trace: memremap+0xcb/0x184 xlate_dev_mem_ptr+0x25/0x2f write_mem+0x94/0xfb vfs_write+0x128/0x26d ksys_write+0xac/0xfe do_syscall_64+0x9a/0xfd entry_SYSCALL_64_after_hwframe+0x4b/0x53 The details of command execution process are as follows. In the above resource tree, "System RAM" is a descendant of "CXL Window 0" instead of a top level resource. So, region_intersects() will report no System RAM resources in the CXL memory region incorrectly, because it only checks the top level resources. Consequently, devmem_is_allowed() will return 1 (allow access via /dev/mem) for CXL memory region incorrectly. Fortunately, ioremap() doesn't allow to map System RAM and reject the access. So, region_intersects() needs to be fixed to work correctly with the resource tree with "System RAM" not at top level as above. To fix it, if we found a unmatched resource in the top level, we will continue to search matched resources in its descendant resources. So, we will not miss any matched resources in resource tree anymore. In the new implementation, an example resource tree |------------- "CXL Window 0" ------------| |-- "System RAM" --| will behave similar as the following fake resource tree for region_intersects(, IORESOURCE_SYSTEM_RAM, ), |-- "System RAM" --||-- "CXL Window 0a" --| Where "CXL Window 0a" is part of the original "CXL Window 0" that isn't covered by "System RAM". Link: https://lkml.kernel.org/r/20240906030713.204292-2-ying.huang@intel.com Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM") Signed-off-by: "Huang, Ying" Cc: Dan Williams Cc: David Hildenbrand Cc: Davidlohr Bueso Cc: Jonathan Cameron Cc: Dave Jiang Cc: Alison Schofield Cc: Vishal Verma Cc: Ira Weiny Cc: Alistair Popple Cc: Andy Shevchenko Cc: Bjorn Helgaas Cc: Baoquan He Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

x86/kaslr: Expose and use the end of the physical memory address space

2024-08-20T11:44:57Z

iounmap() on x86 occasionally fails to unmap because the provided valid ioremap address is not below high_memory. It turned out that this happens due to KASLR. KASLR uses the full address space between PAGE_OFFSET and vaddr_end to randomize the starting points of the direct map, vmalloc and vmemmap regions. It thereby limits the size of the direct map by using the installed memory size plus an extra configurable margin for hot-plug memory. This limitation is done to gain more randomization space because otherwise only the holes between the direct map, vmalloc, vmemmap and vaddr_end would be usable for randomizing. The limited direct map size is not exposed to the rest of the kernel, so the memory hot-plug and resource management related code paths still operate under the assumption that the available address space can be determined with MAX_PHYSMEM_BITS. request_free_mem_region() allocates from (1 << MAX_PHYSMEM_BITS) - 1 downwards. That means the first allocation happens past the end of the direct map and if unlucky this address is in the vmalloc space, which causes high_memory to become greater than VMALLOC_START and consequently causes iounmap() to fail for valid ioremap addresses. MAX_PHYSMEM_BITS cannot be changed for that because the randomization does not align with address bit boundaries and there are other places which actually require to know the maximum number of address bits. All remaining usage sites of MAX_PHYSMEM_BITS have been analyzed and found to be correct. Cure this by exposing the end of the direct map via PHYSMEM_END and use that for the memory hot-plug and resource management related places instead of relying on MAX_PHYSMEM_BITS. In the KASLR case PHYSMEM_END maps to a variable which is initialized by the KASLR initialization and otherwise it is based on MAX_PHYSMEM_BITS as before. To prevent future hickups add a check into add_pages() to catch callers trying to add memory above PHYSMEM_END. Fixes: 0483e1fa6e09 ("x86/mm: Implement ASLR for kernel memory regions") Reported-by: Max Ramanouski Reported-by: Alistair Popple Signed-off-by: Thomas Gleixner Tested-By: Max Ramanouski Tested-by: Alistair Popple Reviewed-by: Dan Williams Reviewed-by: Alistair Popple Reviewed-by: Kees Cook Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/87ed6soy3z.ffs@tglx

resource: Export find_resource_space()

2024-05-28T16:14:14Z

PCI bridge window logic needs to find out in advance to the actual allocation if there is an empty space big enough to fit the window. Export find_resource_space() for the purpose. Also move the struct resource_constraint into generic header to be able to use the new interface. Link: https://lore.kernel.org/r/20240507102523.57320-7-ilpo.jarvinen@linux.intel.com Tested-by: Lidong Wang Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg

resource: Handle simple alignment inside __find_resource_space()

2024-05-28T16:14:14Z

allocate_resource() accepts ->alignf() callback to perform custom alignment beyond constraint->align. If alignf is NULL, simple_align_resource() is used which only returns avail->start (no change). Using avail->start directly is natural and can be done with a conditional in __find_resource_space() instead which avoids unnecessarily using callback. It makes the code inside __find_resource_space() more obvious and removes the need for the caller to provide constraint->alignf unnecessarily. This is preparation for exporting find_resource_space(). Link: https://lore.kernel.org/r/20240507102523.57320-6-ilpo.jarvinen@linux.intel.com Tested-by: Lidong Wang Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg

resource: Use typedef for alignf callback

2024-05-28T16:14:14Z

To make it simpler to declare resource constraint alignf callbacks, add typedef for it and document it. Suggested-by: Andy Shevchenko Link: https://lore.kernel.org/r/20240507102523.57320-5-ilpo.jarvinen@linux.intel.com Tested-by: Lidong Wang Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg

resource: Document find_resource_space() and resource_constraint

2024-05-28T16:14:13Z

Document find_resource_space() and the struct resource_constraint as they are going to be exposed outside of resource.c. Link: https://lore.kernel.org/r/20240507102523.57320-4-ilpo.jarvinen@linux.intel.com Tested-by: Lidong Wang Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg

resource: Rename find_resource() to find_resource_space()

2024-05-28T16:14:13Z

Rename find_resource() to find_resource_space() to better describe what the function does. This is a preparation for exposing it beyond resource.c, which is needed by PCI core. Also rename the __ variant to match the names. Link: https://lore.kernel.org/r/20240507102523.57320-3-ilpo.jarvinen@linux.intel.com Tested-by: Lidong Wang Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg

Merge tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-01-09T19:46:20Z

Pull non-MM updates from Andrew Morton: "Quite a lot of kexec work this time around. Many singleton patches in many places. The notable patch series are: - nilfs2 folio conversion from Matthew Wilcox in 'nilfs2: Folio conversions for file paths'. - Additional nilfs2 folio conversion from Ryusuke Konishi in 'nilfs2: Folio conversions for directory paths'. - IA64 remnant removal in Heiko Carstens's 'Remove unused code after IA-64 removal'. - Arnd Bergmann has enabled the -Wmissing-prototypes warning everywhere in 'Treewide: enable -Wmissing-prototypes'. This had some followup fixes: - Nathan Chancellor has cleaned up the hexagon build in the series 'hexagon: Fix up instances of -Wmissing-prototypes'. - Nathan also addressed some s390 warnings in 's390: A couple of fixes for -Wmissing-prototypes'. - Arnd Bergmann addresses the same warnings for MIPS in his series 'mips: address -Wmissing-prototypes warnings'. - Baoquan He has made kexec_file operate in a top-down-fitting manner similar to kexec_load in the series 'kexec_file: Load kernel at top of system RAM if required' - Baoquan He has also added the self-explanatory 'kexec_file: print out debugging message if required'. - Some checkstack maintenance work from Tiezhu Yang in the series 'Modify some code about checkstack'. - Douglas Anderson has disentangled the watchdog code's logging when multiple reports are occurring simultaneously. The series is 'watchdog: Better handling of concurrent lockups'. - Yuntao Wang has contributed some maintenance work on the crash code in 'crash: Some cleanups and fixes'" * tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (157 commits) crash_core: fix and simplify the logic of crash_exclude_mem_range() x86/crash: use SZ_1M macro instead of hardcoded value x86/crash: remove the unused image parameter from prepare_elf_headers() kdump: remove redundant DEFAULT_CRASH_KERNEL_LOW_SIZE scripts/decode_stacktrace.sh: strip unexpected CR from lines watchdog: if panicking and we dumped everything, don't re-enable dumping watchdog/hardlockup: use printk_cpu_sync_get_irqsave() to serialize reporting watchdog/softlockup: use printk_cpu_sync_get_irqsave() to serialize reporting watchdog/hardlockup: adopt softlockup logic avoiding double-dumps kexec_core: fix the assignment to kimage->control_page x86/kexec: fix incorrect end address passed to kernel_ident_mapping_init() lib/trace_readwrite.c:: replace asm-generic/io with linux/io nilfs2: cpfile: fix some kernel-doc warnings stacktrace: fix kernel-doc typo scripts/checkstack.pl: fix no space expression between sp and offset x86/kexec: fix incorrect argument passed to kexec_dprintk() x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs nilfs2: add missing set_freezable() for freezable kthread kernel: relay: remove relay_file_splice_read dead code, doesn't work docs: submit-checklist: remove all of "make namespacecheck" ...

resource: add walk_system_ram_res_rev()

2023-12-11T01:21:44Z

This function, being a variant of walk_system_ram_res() introduced in commit 8c86e70acead ("resource: provide new functions to walk through resources"), walks through a list of all the resources of System RAM in reversed order, i.e., from higher to lower. It will be used in kexec_file code to load kernel, initrd etc when preparing kexec reboot. Link: https://lkml.kernel.org/r/ZVTA6z/06cLnWKUz@MiWiFi-R3L-srv Signed-off-by: AKASHI Takahiro Signed-off-by: Baoquan He Cc: Eric Biederman Signed-off-by: Andrew Morton

kernel/resource: Increment by align value in get_free_mem_region()

2023-12-05T01:19:03Z

Currently get_free_mem_region() searches for available capacity in increments equal to the region size being requested. This can cause the search to take giant steps through the resource leaving needless gaps and missing available space. Specifically 'cxl create-region' fails with ERANGE even though capacity of the given size and CXL's expected 256M x InterleaveWays alignment can be satisfied. Replace the total-request-size increment with a next alignment increment so that the next possible address is always examined for availability. Fixes: 14b80582c43e ("resource: Introduce alloc_free_mem_region()") Reported-by: Dmytro Adamenko Reported-by: Dan Williams Signed-off-by: Alison Schofield Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/20231113221324.1118092-1-alison.schofield@intel.com Cc: Jason Gunthorpe Reviewed-by: Christoph Hellwig Signed-off-by: Dan Williams