linux/kernel, branch v5.2

ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME

2019-07-04T17:00:41Z

Fix two issues: When called for PTRACE_TRACEME, ptrace_link() would obtain an RCU reference to the parent's objective credentials, then give that pointer to get_cred(). However, the object lifetime rules for things like struct cred do not permit unconditionally turning an RCU reference into a stable reference. PTRACE_TRACEME records the parent's credentials as if the parent was acting as the subject, but that's not the case. If a malicious unprivileged child uses PTRACE_TRACEME and the parent is privileged, and at a later point, the parent process becomes attacker-controlled (because it drops privileges and calls execve()), the attacker ends up with control over two processes with a privileged ptrace relationship, which can be abused to ptrace a suid binary and obtain root privileges. Fix both of these by always recording the credentials of the process that is requesting the creation of the ptrace relationship: current_cred() can't change under us, and current is the proper subject for access control. This change is theoretically userspace-visible, but I am not aware of any code that it will actually break. Fixes: 64b875f7ac8a ("ptrace: Capture the ptracer's creds not PT_PTRACE_CAP") Signed-off-by: Jann Horn Acked-by: Oleg Nesterov Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds

Merge tag 'trace-v5.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2019-07-04T01:26:17Z

Pull tracing fixes from Steven Rostedt: "This includes three fixes: - Fix a deadlock from a previous fix to keep module loading and function tracing text modifications from stepping on each other (this has a few patches to help document the issue in comments) - Fix a crash when the snapshot buffer gets out of sync with the main ring buffer - Fix a memory leak when reading the memory logs" * tag 'trace-v5.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace/x86: Anotate text_mutex split between ftrace_arch_code_modify_post_process() and ftrace_arch_code_modify_prepare() tracing/snapshot: Resize spare buffer if size changed tracing: Fix memory leak in tracing_err_log_open() ftrace/x86: Add a comment to why we take text_mutex in ftrace_arch_code_modify_prepare() ftrace/x86: Remove possible deadlock between register_kprobe() and ftrace_run_update_code()

fork: return proper negative error code

2019-07-01T14:43:30Z

Make sure to return a proper negative error code from copy_process() when anon_inode_getfile() fails with CLONE_PIDFD. Otherwise _do_fork() will not detect an error and get_task_pid() will operator on a nonsensical pointer: R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c R13: 00007ffc15fbb0ff R14: 00007ff07e47e9c0 R15: 0000000000000000 kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7990 Comm: syz-executor290 Not tainted 5.2.0-rc6+ #9 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:194 [inline] RIP: 0010:get_task_pid+0xe1/0x210 kernel/pid.c:372 Code: 89 ff e8 62 27 5f 00 49 8b 07 44 89 f1 4c 8d bc c8 90 01 00 00 eb 0c e8 0d fe 25 00 49 81 c7 38 05 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ff e8 31 27 5f 00 4d 8b 37 e8 f9 47 12 00 RSP: 0018:ffff88808a4a7d78 EFLAGS: 00010203 RAX: 00000000000000a7 RBX: dffffc0000000000 RCX: ffff888088180600 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88808a4a7d90 R08: ffffffff814fb3a8 R09: ffffed1015d66bf8 R10: ffffed1015d66bf8 R11: 1ffff11015d66bf7 R12: 0000000000041ffc R13: 1ffff11011494fbc R14: 0000000000000000 R15: 000000000000053d FS: 00007ff07e47e700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004b5100 CR3: 0000000094df2000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: _do_fork+0x1b9/0x5f0 kernel/fork.c:2360 __do_sys_clone kernel/fork.c:2454 [inline] __se_sys_clone kernel/fork.c:2448 [inline] __x64_sys_clone+0xc1/0xd0 kernel/fork.c:2448 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Link: https://lore.kernel.org/lkml/000000000000e0dc0d058c9e7142@google.com Reported-and-tested-by: syzbot+002e636502bc4b64eb5c@syzkaller.appspotmail.com Fixes: 6fd2fe494b17 ("copy_process(): don't use ksys_close() on cleanups") Cc: Jann Horn Cc: Al Viro Signed-off-by: Christian Brauner

Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-06-30T03:19:17Z

Pull SMP fixes from Thomas Gleixner: "Two small changes for the cpu hotplug code: - Prevent out of bounds access which actually might crash the machine caused by a missing bounds check in the fail injection code - Warn about unsupported migitation mode command line arguments to make people aware that they typoed the paramater. Not necessarily a fix but quite some people tripped over that" * 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpu/hotplug: Fix out-of-bounds read when setting fail state cpu/speculation: Warn on unsupported mitigations= parameter

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-06-29T11:39:17Z

Pull perf fixes from Ingo Molnar: "Various fixes, most of them related to bugs perf fuzzing found in the x86 code" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/x86/regs: Use PERF_REG_EXTENDED_MASK perf/x86: Remove pmu->pebs_no_xmm_regs perf/x86: Clean up PEBS_XMM_REGS perf/x86/regs: Check reserved bits perf/x86: Disable extended registers for non-supported PMUs perf/ioctl: Add check for the sample_period value perf/core: Fix perf_sample_regs_user() mm check

Merge tag 'pm-5.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2019-06-29T11:29:45Z

Pull power management fix from Rafael Wysocki: "Avoid skipping bus-level PCI power management during system resume for PCIe ports left in D0 during the preceding suspend transition on platforms where the power states of those ports can change out of the PCI layer's control" * tag 'pm-5.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: PCI: PM: Avoid skipping bus-level PM on platforms without ACPI

fork,memcg: alloc_thread_stack_node needs to set tsk->stack

2019-06-29T08:43:45Z

Commit 5eed6f1dff87 ("fork,memcg: fix crash in free_thread_stack on memcg charge fail") corrected two instances, but there was a third instance of this bug. Without setting tsk->stack, if memcg_charge_kernel_stack fails, it'll execute free_thread_stack() on a dangling pointer. Enterprise kernels are compiled with VMAP_STACK=y so this isn't critical, but custom VMAP_STACK=n builds should have some performance advantage, with the drawback of risking to fail fork because compaction didn't succeed. So as long as VMAP_STACK=n is a supported option it's worth fixing it upstream. Link: http://lkml.kernel.org/r/20190619011450.28048-1-aarcange@redhat.com Fixes: 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting") Signed-off-by: Andrea Arcangeli Reviewed-by: Rik van Riel Acked-by: Roman Gushchin Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

signal: remove the wrong signal_pending() check in restore_user_sigmask()

2019-06-29T08:43:45Z

This is the minimal fix for stable, I'll send cleanups later. Commit 854a6ed56839 ("signal: Add restore_user_sigmask()") introduced the visible change which breaks user-space: a signal temporary unblocked by set_user_sigmask() can be delivered even if the caller returns success or timeout. Change restore_user_sigmask() to accept the additional "interrupted" argument which should be used instead of signal_pending() check, and update the callers. Eric said: : For clarity. I don't think this is required by posix, or fundamentally to : remove the races in select. It is what linux has always done and we have : applications who care so I agree this fix is needed. : : Further in any case where the semantic change that this patch rolls back : (aka where allowing a signal to be delivered and the select like call to : complete) would be advantage we can do as well if not better by using : signalfd. : : Michael is there any chance we can get this guarantee of the linux : implementation of pselect and friends clearly documented. The guarantee : that if the system call completes successfully we are guaranteed that no : signal that is unblocked by using sigmask will be delivered? Link: http://lkml.kernel.org/r/20190604134117.GA29963@redhat.com Fixes: 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add restore_user_sigmask()") Signed-off-by: Oleg Nesterov Reported-by: Eric Wong Tested-by: Eric Wong Acked-by: "Eric W. Biederman" Acked-by: Arnd Bergmann Acked-by: Deepa Dinamani Cc: Michael Kerrisk Cc: Jens Axboe Cc: Davidlohr Bueso Cc: Jason Baron Cc: Thomas Gleixner Cc: Al Viro Cc: David Laight Cc: [5.0+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

tracing/snapshot: Resize spare buffer if size changed

2019-06-28T18:58:52Z

Current snapshot implementation swaps two ring_buffers even though their sizes are different from each other, that can cause an inconsistency between the contents of buffer_size_kb file and the current buffer size. For example: # cat buffer_size_kb 7 (expanded: 1408) # echo 1 > events/enable # grep bytes per_cpu/cpu0/stats bytes: 1441020 # echo 1 > snapshot // current:1408, spare:1408 # echo 123 > buffer_size_kb // current:123, spare:1408 # echo 1 > snapshot // current:1408, spare:123 # grep bytes per_cpu/cpu0/stats bytes: 1443700 # cat buffer_size_kb 123 // != current:1408 And also, a similar per-cpu case hits the following WARNING: Reproducer: # echo 1 > per_cpu/cpu0/snapshot # echo 123 > buffer_size_kb # echo 1 > per_cpu/cpu0/snapshot WARNING: WARNING: CPU: 0 PID: 1946 at kernel/trace/trace.c:1607 update_max_tr_single.part.0+0x2b8/0x380 Modules linked in: CPU: 0 PID: 1946 Comm: bash Not tainted 5.2.0-rc6 #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014 RIP: 0010:update_max_tr_single.part.0+0x2b8/0x380 Code: ff e8 dc da f9 ff 0f 0b e9 88 fe ff ff e8 d0 da f9 ff 44 89 ee bf f5 ff ff ff e8 33 dc f9 ff 41 83 fd f5 74 96 e8 b8 da f9 ff <0f> 0b eb 8d e8 af da f9 ff 0f 0b e9 bf fd ff ff e8 a3 da f9 ff 48 RSP: 0018:ffff888063e4fca0 EFLAGS: 00010093 RAX: ffff888066214380 RBX: ffffffff99850fe0 RCX: ffffffff964298a8 RDX: 0000000000000000 RSI: 00000000fffffff5 RDI: 0000000000000005 RBP: 1ffff1100c7c9f96 R08: ffff888066214380 R09: ffffed100c7c9f9b R10: ffffed100c7c9f9a R11: 0000000000000003 R12: 0000000000000000 R13: 00000000ffffffea R14: ffff888066214380 R15: ffffffff99851060 FS: 00007f9f8173c700(0000) GS:ffff88806d000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000714dc0 CR3: 0000000066fa6000 CR4: 00000000000006f0 Call Trace: ? trace_array_printk_buf+0x140/0x140 ? __mutex_lock_slowpath+0x10/0x10 tracing_snapshot_write+0x4c8/0x7f0 ? trace_printk_init_buffers+0x60/0x60 ? selinux_file_permission+0x3b/0x540 ? tracer_preempt_off+0x38/0x506 ? trace_printk_init_buffers+0x60/0x60 __vfs_write+0x81/0x100 vfs_write+0x1e1/0x560 ksys_write+0x126/0x250 ? __ia32_sys_read+0xb0/0xb0 ? do_syscall_64+0x1f/0x390 do_syscall_64+0xc1/0x390 entry_SYSCALL_64_after_hwframe+0x49/0xbe This patch adds resize_buffer_duplicate_size() to check if there is a difference between current/spare buffer sizes and resize a spare buffer if necessary. Link: http://lkml.kernel.org/r/20190625012910.13109-1-devel@etsukata.com Cc: stable@vger.kernel.org Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions") Signed-off-by: Eiichi Tsukata Signed-off-by: Steven Rostedt (VMware)

tracing: Fix memory leak in tracing_err_log_open()

2019-06-28T18:57:23Z

When tracing_err_log_open() calls seq_open(), allocated memory is not freed. kmemleak report: unreferenced object 0xffff92c0781d1100 (size 128): comm "tail", pid 15116, jiffies 4295163855 (age 22.704s) hex dump (first 32 bytes): 00 f0 08 e5 c0 92 ff ff 00 10 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<000000000d0687d5>] kmem_cache_alloc+0x11f/0x1e0 [<000000003e3039a8>] seq_open+0x2f/0x90 [<000000008dd36b7d>] tracing_err_log_open+0x67/0x140 [<000000005a431ae2>] do_dentry_open+0x1df/0x3a0 [<00000000a2910603>] vfs_open+0x2f/0x40 [<0000000038b0a383>] path_openat+0x2e8/0x1690 [<00000000fe025bda>] do_filp_open+0x9b/0x110 [<00000000483a5091>] do_sys_open+0x1ba/0x260 [<00000000c558b5fd>] __x64_sys_openat+0x20/0x30 [<000000006881ec07>] do_syscall_64+0x5a/0x130 [<00000000571c2e94>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by calling seq_release() in tracing_err_log_fops.release(). Link: http://lkml.kernel.org/r/20190628105640.GA1863@DESKTOP Fixes: 8a062902be725 ("tracing: Add tracing error log") Reviewed-by: Tom Zanussi Signed-off-by: Takeshi Misawa Signed-off-by: Steven Rostedt (VMware)