kernel/linux.git/fs/proc, branch v5.15.65

mm/smaps: don't access young/dirty bit if pte unpresent

2022-08-31T15:16:37+00:00

[ Upstream commit efd4149342db2df41b1bbe68972ead853b30e444 ] These bits should only be valid when the ptes are present. Introducing two booleans for it and set it to false when !pte_present() for both pte and pmd accountings. The bug is found during code reading and no real world issue reported, but logically such an error can cause incorrect readings for either smaps or smaps_rollup output on quite a few fields. For example, it could cause over-estimate on values like Shared_Dirty, Private_Dirty, Referenced. Or it could also cause under-estimate on values like LazyFree, Shared_Clean, Private_Clean. Link: https://lkml.kernel.org/r/20220805160003.58929-1-peterx@redhat.com Fixes: b1d4d9e0cbd0 ("proc/smaps: carefully handle migration entries") Fixes: c94b6923fa0a ("/proc/PID/smaps: Add PMD migration entry parsing") Signed-off-by: Peter Xu Reviewed-by: Vlastimil Babka Reviewed-by: David Hildenbrand Reviewed-by: Yang Shi Cc: Konstantin Khlebnikov Cc: Huang Ying Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

proc: fix a dentry lock race between release_task and lookup

2022-08-17T12:24:08+00:00

[ Upstream commit d919a1e79bac890421537cf02ae773007bf55e6b ] Commit 7bc3e6e55acf06 ("proc: Use a list of inodes to flush from proc") moved proc_flush_task() behind __exit_signal(). Then, process systemd can take long period high cpu usage during releasing task in following concurrent processes: systemd ps kernel_waitid stat(/proc/tgid) do_wait filename_lookup wait_consider_task lookup_fast release_task __exit_signal __unhash_process detach_pid __change_pid // remove task->pid_links d_revalidate -> pid_revalidate // 0 d_invalidate(/proc/tgid) shrink_dcache_parent(/proc/tgid) d_walk(/proc/tgid) spin_lock_nested(/proc/tgid/fd) // iterating opened fd proc_flush_pid | d_invalidate (/proc/tgid/fd) | shrink_dcache_parent(/proc/tgid/fd) | shrink_dentry_list(subdirs) ↓ shrink_lock_dentry(/proc/tgid/fd) --> race on dentry lock Function d_invalidate() will remove dentry from hash firstly, but why does proc_flush_pid() process dentry '/proc/tgid/fd' before dentry '/proc/tgid'? That's because proc_pid_make_inode() adds proc inode in reverse order by invoking hlist_add_head_rcu(). But proc should not add any inodes under '/proc/tgid' except '/proc/tgid/task/pid', fix it by adding inode into 'pid->inodes' only if the inode is /proc/tgid or /proc/tgid/task/pid. Performance regression: Create 200 tasks, each task open one file for 50,000 times. Kill all tasks when opened files exceed 10,000,000 (cat /proc/sys/fs/file-nr). Before fix: $ time killall -wq aa real 4m40.946s # During this period, we can see 'ps' and 'systemd' taking high cpu usage. After fix: $ time killall -wq aa real 1m20.732s # During this period, we can see 'systemd' taking high cpu usage. Link: https://lkml.kernel.org/r/20220713130029.4133533-1-chengzhihao1@huawei.com Fixes: 7bc3e6e55acf06 ("proc: Use a list of inodes to flush from proc") Link: https://bugzilla.kernel.org/show_bug.cgi?id=216054 Signed-off-by: Zhihao Cheng Signed-off-by: Zhang Yi Suggested-by: Brian Foster Reviewed-by: Brian Foster Cc: Al Viro Cc: Alexey Dobriyan Cc: Eric Biederman Cc: Matthew Wilcox Cc: Baoquan He Cc: Kalesh Singh Cc: Yu Kuai Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

sysctl: move some boundary constants from sysctl.c to sysctl_vals

2022-07-29T15:25:11+00:00

[ Upstream commit 78e36f3b0dae586f623c4a37ec5eb5496f5abbe1 ] sysctl has helpers which let us specify boundary values for a min or max int value. Since these are used for a boundary check only they don't change, so move these variables to sysctl_vals to avoid adding duplicate variables. This will help with our cleanup of kernel/sysctl.c. [akpm@linux-foundation.org: update it for "mm/pagealloc: sysctl: change watermark_scale_factor max limit to 30%"] [mcgrof@kernel.org: major rebase] Link: https://lkml.kernel.org/r/20211123202347.818157-3-mcgrof@kernel.org Signed-off-by: Xiaoming Ni Signed-off-by: Luis Chamberlain Reviewed-by: Kees Cook Cc: Al Viro Cc: Amir Goldstein Cc: Andy Shevchenko Cc: Benjamin LaHaise Cc: "Eric W. Biederman" Cc: Greg Kroah-Hartman Cc: Iurii Zaikin Cc: Jan Kara Cc: Paul Turner Cc: Peter Zijlstra Cc: Petr Mladek Cc: Qing Wang Cc: Sebastian Reichel Cc: Sergey Senozhatsky Cc: Stephen Kitt Cc: Tetsuo Handa Cc: Antti Palosaari Cc: Arnd Bergmann Cc: Benjamin Herrenschmidt Cc: Clemens Ladisch Cc: David Airlie Cc: Jani Nikula Cc: Joel Becker Cc: Joonas Lahtinen Cc: Joseph Qi Cc: Julia Lawall Cc: Lukas Middendorf Cc: Mark Fasheh Cc: Phillip Potter Cc: Rodrigo Vivi Cc: Douglas Gilbert Cc: James E.J. Bottomley Cc: Jani Nikula Cc: John Ogness Cc: Martin K. Petersen Cc: "Rafael J. Wysocki" Cc: Steven Rostedt (VMware) Cc: Suren Baghdasaryan Cc: "Theodore Ts'o" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

proc: fix dentry/inode overinstantiating under /proc/${pid}/net

2022-06-09T08:23:10+00:00

[ Upstream commit 7055197705709c59b8ab77e6a5c7d46d61edd96e ] When a process exits, /proc/${pid}, and /proc/${pid}/net dentries are flushed. However some leaf dentries like /proc/${pid}/net/arp_cache aren't. That's because respective PDEs have proc_misc_d_revalidate() hook which returns 1 and leaves dentries/inodes in the LRU. Force revalidation/lookup on everything under /proc/${pid}/net by inheriting proc_net_dentry_ops. [akpm@linux-foundation.org: coding-style cleanups] Link: https://lkml.kernel.org/r/YjdVHgildbWO7diJ@localhost.localdomain Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)") Signed-off-by: Alexey Dobriyan Reported-by: hui li Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

procfs: prevent unprivileged processes accessing fdinfo dir

2022-05-18T08:26:50+00:00

[ Upstream commit 1927e498aee1757b3df755a194cbfc5cc0f2b663 ] The file permissions on the fdinfo dir from were changed from S_IRUSR|S_IXUSR to S_IRUGO|S_IXUGO, and a PTRACE_MODE_READ check was added for opening the fdinfo files [1]. However, the ptrace permission check was not added to the directory, allowing anyone to get the open FD numbers by reading the fdinfo directory. Add the missing ptrace permission check for opening the fdinfo directory. [1] https://lkml.kernel.org/r/20210308170651.919148-1-kaleshsingh@google.com Link: https://lkml.kernel.org/r/20210713162008.1056986-1-kaleshsingh@google.com Fixes: 7bc3fa0172a4 ("procfs: allow reading fdinfo with PTRACE_MODE_READ") Signed-off-by: Kalesh Singh Cc: Kees Cook Cc: Eric W. Biederman Cc: Christian Brauner Cc: Suren Baghdasaryan Cc: Hridya Valsaraju Cc: Jann Horn Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

proc: bootconfig: Add null pointer check

2022-04-08T12:24:12+00:00

commit bed5b60bf67ccd8957b8c0558fead30c4a3f5d3f upstream. kzalloc is a memory allocation function which can return NULL when some internal memory errors happen. It is safer to add null pointer check. Link: https://lkml.kernel.org/r/20220329104004.2376879-1-lv.ruyi@zte.com.cn Cc: stable@vger.kernel.org Fixes: c1a3c36017d4 ("proc: bootconfig: Add /proc/bootconfig to show boot config list") Acked-by: Masami Hiramatsu Reported-by: Zeal Robot Signed-off-by: Lv Ruyi Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

proc: fix documentation and description of pagemap

2022-03-08T18:12:54+00:00

commit dd21bfa425c098b95ca86845f8e7d1ec1ddf6e4a upstream. Since bit 57 was exported for uffd-wp write-protected (commit fb8e37f35a2f: "mm/pagemap: export uffd-wp protection information"), fixing it can reduce some unnecessary confusion. Link: https://lkml.kernel.org/r/20220301044538.3042713-1-yun.zhou@windriver.com Fixes: fb8e37f35a2fe1 ("mm/pagemap: export uffd-wp protection information") Signed-off-by: Yun Zhou Reviewed-by: Peter Xu Cc: Jonathan Corbet Cc: Tiberiu A Georgescu Cc: Florian Schmidt Cc: Ivan Teterevkov Cc: SeongJae Park Cc: Yang Shi Cc: David Hildenbrand Cc: Axel Rasmussen Cc: Miaohe Lin Cc: Andrea Arcangeli Cc: Colin Cross Cc: Alistair Popple Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

fs/proc: task_mmu.c: don't read mapcount for migration entry

2022-02-23T11:03:02+00:00

commit 24d7275ce2791829953ed4e72f68277ceb2571c6 upstream. The syzbot reported the below BUG: kernel BUG at include/linux/page-flags.h:785! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 4392 Comm: syz-executor560 Not tainted 5.16.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:PageDoubleMap include/linux/page-flags.h:785 [inline] RIP: 0010:__page_mapcount+0x2d2/0x350 mm/util.c:744 Call Trace: page_mapcount include/linux/mm.h:837 [inline] smaps_account+0x470/0xb10 fs/proc/task_mmu.c:466 smaps_pte_entry fs/proc/task_mmu.c:538 [inline] smaps_pte_range+0x611/0x1250 fs/proc/task_mmu.c:601 walk_pmd_range mm/pagewalk.c:128 [inline] walk_pud_range mm/pagewalk.c:205 [inline] walk_p4d_range mm/pagewalk.c:240 [inline] walk_pgd_range mm/pagewalk.c:277 [inline] __walk_page_range+0xe23/0x1ea0 mm/pagewalk.c:379 walk_page_vma+0x277/0x350 mm/pagewalk.c:530 smap_gather_stats.part.0+0x148/0x260 fs/proc/task_mmu.c:768 smap_gather_stats fs/proc/task_mmu.c:741 [inline] show_smap+0xc6/0x440 fs/proc/task_mmu.c:822 seq_read_iter+0xbb0/0x1240 fs/seq_file.c:272 seq_read+0x3e0/0x5b0 fs/seq_file.c:162 vfs_read+0x1b5/0x600 fs/read_write.c:479 ksys_read+0x12d/0x250 fs/read_write.c:619 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae The reproducer was trying to read /proc/$PID/smaps when calling MADV_FREE at the mean time. MADV_FREE may split THPs if it is called for partial THP. It may trigger the below race: CPU A CPU B ----- ----- smaps walk: MADV_FREE: page_mapcount() PageCompound() split_huge_page() page = compound_head(page) PageDoubleMap(page) When calling PageDoubleMap() this page is not a tail page of THP anymore so the BUG is triggered. This could be fixed by elevated refcount of the page before calling mapcount, but that would prevent it from counting migration entries, and it seems overkilling because the race just could happen when PMD is split so all PTE entries of tail pages are actually migration entries, and smaps_account() does treat migration entries as mapcount == 1 as Kirill pointed out. Add a new parameter for smaps_account() to tell this entry is migration entry then skip calling page_mapcount(). Don't skip getting mapcount for device private entries since they do track references with mapcount. Pagemap also has the similar issue although it was not reported. Fixed it as well. [shy828301@gmail.com: v4] Link: https://lkml.kernel.org/r/20220203182641.824731-1-shy828301@gmail.com [nathan@kernel.org: avoid unused variable warning in pagemap_pmd_range()] Link: https://lkml.kernel.org/r/20220207171049.1102239-1-nathan@kernel.org Link: https://lkml.kernel.org/r/20220120202805.3369-1-shy828301@gmail.com Fixes: e9b61f19858a ("thp: reintroduce split_huge_page()") Signed-off-by: Yang Shi Signed-off-by: Nathan Chancellor Reported-by: syzbot+1f52b3a18d5633fa7f82@syzkaller.appspotmail.com Acked-by: David Hildenbrand Cc: "Kirill A. Shutemov" Cc: Jann Horn Cc: Matthew Wilcox Cc: Alexey Dobriyan Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

proc/vmcore: fix clearing user buffer by properly using clear_user()

2021-12-01T08:04:44+00:00

commit c1e63117711977cc4295b2ce73de29dd17066c82 upstream. To clear a user buffer we cannot simply use memset, we have to use clear_user(). With a virtio-mem device that registers a vmcore_cb and has some logically unplugged memory inside an added Linux memory block, I can easily trigger a BUG by copying the vmcore via "cp": systemd[1]: Starting Kdump Vmcore Save Service... kdump[420]: Kdump is using the default log level(3). kdump[453]: saving to /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/ kdump[458]: saving vmcore-dmesg.txt to /sysroot/var/crash/127.0.0.1-2021-11-11-14:59:22/ kdump[465]: saving vmcore-dmesg.txt complete kdump[467]: saving vmcore BUG: unable to handle page fault for address: 00007f2374e01000 #PF: supervisor write access in kernel mode #PF: error_code(0x0003) - permissions violation PGD 7a523067 P4D 7a523067 PUD 7a528067 PMD 7a525067 PTE 800000007048f867 Oops: 0003 [#1] PREEMPT SMP NOPTI CPU: 0 PID: 468 Comm: cp Not tainted 5.15.0+ #6 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 04/01/2014 RIP: 0010:read_from_oldmem.part.0.cold+0x1d/0x86 Code: ff ff ff e8 05 ff fe ff e9 b9 e9 7f ff 48 89 de 48 c7 c7 38 3b 60 82 e8 f1 fe fe ff 83 fd 08 72 3c 49 8d 7d 08 4c 89 e9 89 e8 <49> c7 45 00 00 00 00 00 49 c7 44 05 f8 00 00 00 00 48 83 e7 f81 RSP: 0018:ffffc9000073be08 EFLAGS: 00010212 RAX: 0000000000001000 RBX: 00000000002fd000 RCX: 00007f2374e01000 RDX: 0000000000000001 RSI: 00000000ffffdfff RDI: 00007f2374e01008 RBP: 0000000000001000 R08: 0000000000000000 R09: ffffc9000073bc50 R10: ffffc9000073bc48 R11: ffffffff829461a8 R12: 000000000000f000 R13: 00007f2374e01000 R14: 0000000000000000 R15: ffff88807bd421e8 FS: 00007f2374e12140(0000) GS:ffff88807f000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f2374e01000 CR3: 000000007a4aa000 CR4: 0000000000350eb0 Call Trace: read_vmcore+0x236/0x2c0 proc_reg_read+0x55/0xa0 vfs_read+0x95/0x190 ksys_read+0x4f/0xc0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Some x86-64 CPUs have a CPU feature called "Supervisor Mode Access Prevention (SMAP)", which is used to detect wrong access from the kernel to user buffers like this: SMAP triggers a permissions violation on wrong access. In the x86-64 variant of clear_user(), SMAP is properly handled via clac()+stac(). To fix, properly use clear_user() when we're dealing with a user buffer. Link: https://lkml.kernel.org/r/20211112092750.6921-1-david@redhat.com Fixes: 997c136f518c ("fs/proc/vmcore.c: add hook to read_from_oldmem() to check for non-ram pages") Signed-off-by: David Hildenbrand Acked-by: Baoquan He Cc: Dave Young Cc: Baoquan He Cc: Vivek Goyal Cc: Philipp Rudo Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

fs/proc/uptime.c: Fix idle time reporting in /proc/uptime

2021-11-18T18:16:13+00:00

[ Upstream commit a130e8fbc7de796eb6e680724d87f4737a26d0ac ] /proc/uptime reports idle time by reading the CPUTIME_IDLE field from the per-cpu kcpustats. However, on NO_HZ systems, idle time is not continually updated on idle cpus, leading this value to appear incorrectly small. /proc/stat performs an accounting update when reading idle time; we can use the same approach for uptime. With this patch, /proc/stat and /proc/uptime now agree on idle time. Additionally, the following shows idle time tick up consistently on an idle machine: (while true; do cat /proc/uptime; sleep 1; done) | awk '{print $2-prev; prev=$2}' Reported-by: Luigi Rizzo Signed-off-by: Josh Don Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Eric Dumazet Link: https://lkml.kernel.org/r/20210827165438.3280779-1-joshdon@google.com Signed-off-by: Sasha Levin