From 621b6d2ea297d0fb6030452c5bcd221f12165fcf Mon Sep 17 00:00:00 2001 From: Prashant Bhole Date: Mon, 9 Apr 2018 19:03:46 +0900 Subject: perf/core: Fix use-after-free in uprobe_perf_close() A use-after-free bug was caught by KASAN while running usdt related code (BCC project. bcc/tests/python/test_usdt2.py): ================================================================== BUG: KASAN: use-after-free in uprobe_perf_close+0x222/0x3b0 Read of size 4 at addr ffff880384f9b4a4 by task test_usdt2.py/870 CPU: 4 PID: 870 Comm: test_usdt2.py Tainted: G W 4.16.0-next-20180409 #215 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0xc7/0x15b ? show_regs_print_info+0x5/0x5 ? printk+0x9c/0xc3 ? kmsg_dump_rewind_nolock+0x6e/0x6e ? uprobe_perf_close+0x222/0x3b0 print_address_description+0x83/0x3a0 ? uprobe_perf_close+0x222/0x3b0 kasan_report+0x1dd/0x460 ? uprobe_perf_close+0x222/0x3b0 uprobe_perf_close+0x222/0x3b0 ? probes_open+0x180/0x180 ? free_filters_list+0x290/0x290 trace_uprobe_register+0x1bb/0x500 ? perf_event_attach_bpf_prog+0x310/0x310 ? probe_event_disable+0x4e0/0x4e0 perf_uprobe_destroy+0x63/0xd0 _free_event+0x2bc/0xbd0 ? lockdep_rcu_suspicious+0x100/0x100 ? ring_buffer_attach+0x550/0x550 ? kvm_sched_clock_read+0x1a/0x30 ? perf_event_release_kernel+0x3e4/0xc00 ? __mutex_unlock_slowpath+0x12e/0x540 ? wait_for_completion+0x430/0x430 ? lock_downgrade+0x3c0/0x3c0 ? lock_release+0x980/0x980 ? do_raw_spin_trylock+0x118/0x150 ? do_raw_spin_unlock+0x121/0x210 ? do_raw_spin_trylock+0x150/0x150 perf_event_release_kernel+0x5d4/0xc00 ? put_event+0x30/0x30 ? fsnotify+0xd2d/0xea0 ? sched_clock_cpu+0x18/0x1a0 ? __fsnotify_update_child_dentry_flags.part.0+0x1b0/0x1b0 ? pvclock_clocksource_read+0x152/0x2b0 ? pvclock_read_flags+0x80/0x80 ? kvm_sched_clock_read+0x1a/0x30 ? sched_clock_cpu+0x18/0x1a0 ? pvclock_clocksource_read+0x152/0x2b0 ? locks_remove_file+0xec/0x470 ? pvclock_read_flags+0x80/0x80 ? fcntl_setlk+0x880/0x880 ? ima_file_free+0x8d/0x390 ? lockdep_rcu_suspicious+0x100/0x100 ? ima_file_check+0x110/0x110 ? fsnotify+0xea0/0xea0 ? kvm_sched_clock_read+0x1a/0x30 ? rcu_note_context_switch+0x600/0x600 perf_release+0x21/0x40 __fput+0x264/0x620 ? fput+0xf0/0xf0 ? do_raw_spin_unlock+0x121/0x210 ? do_raw_spin_trylock+0x150/0x150 ? SyS_fchdir+0x100/0x100 ? fsnotify+0xea0/0xea0 task_work_run+0x14b/0x1e0 ? task_work_cancel+0x1c0/0x1c0 ? copy_fd_bitmaps+0x150/0x150 ? vfs_read+0xe5/0x260 exit_to_usermode_loop+0x17b/0x1b0 ? trace_event_raw_event_sys_exit+0x1a0/0x1a0 do_syscall_64+0x3f6/0x490 ? syscall_return_slowpath+0x2c0/0x2c0 ? lockdep_sys_exit+0x1f/0xaa ? syscall_return_slowpath+0x1a3/0x2c0 ? lockdep_sys_exit+0x1f/0xaa ? prepare_exit_to_usermode+0x11c/0x1e0 ? enter_from_user_mode+0x30/0x30 random: crng init done ? __put_user_4+0x1c/0x30 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x7f41d95f9340 RSP: 002b:00007fffe71e4268 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 000000000000000d RCX: 00007f41d95f9340 RDX: 0000000000000000 RSI: 0000000000002401 RDI: 000000000000000d RBP: 0000000000000000 R08: 00007f41ca8ff700 R09: 00007f41d996dd1f R10: 00007fffe71e41e0 R11: 0000000000000246 R12: 00007fffe71e4330 R13: 0000000000000000 R14: fffffffffffffffc R15: 00007fffe71e4290 Allocated by task 870: kasan_kmalloc+0xa0/0xd0 kmem_cache_alloc_node+0x11a/0x430 copy_process.part.19+0x11a0/0x41c0 _do_fork+0x1be/0xa20 do_syscall_64+0x198/0x490 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Freed by task 0: __kasan_slab_free+0x12e/0x180 kmem_cache_free+0x102/0x4d0 free_task+0xfe/0x160 __put_task_struct+0x189/0x290 delayed_put_task_struct+0x119/0x250 rcu_process_callbacks+0xa6c/0x1b60 __do_softirq+0x238/0x7ae The buggy address belongs to the object at ffff880384f9b480 which belongs to the cache task_struct of size 12928 It occurs because task_struct is freed before perf_event which refers to the task and task flags are checked while teardown of the event. perf_event_alloc() assigns task_struct to hw.target of perf_event, but there is no reference counting for it. As a fix we get_task_struct() in perf_event_alloc() at above mentioned assignment and put_task_struct() in _free_event(). Signed-off-by: Prashant Bhole Reviewed-by: Oleg Nesterov Acked-by: Peter Zijlstra (Intel) Cc: Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 63b6da39bb38e8f1a1ef3180d32a39d6 ("perf: Fix perf_event_exit_task() race") Link: http://lkml.kernel.org/r/20180409100346.6416-1-bhole_prashant_q7@lab.ntt.co.jp Signed-off-by: Ingo Molnar --- kernel/events/core.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index fc1c330c6bd6..d7af82827373 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4447,6 +4447,9 @@ static void _free_event(struct perf_event *event) if (event->ctx) put_ctx(event->ctx); + if (event->hw.target) + put_task_struct(event->hw.target); + exclusive_event_destroy(event); module_put(event->pmu->module); @@ -9955,6 +9958,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, * and we cannot use the ctx information because we need the * pmu before we get a ctx. */ + get_task_struct(task); event->hw.target = task; } @@ -10070,6 +10074,8 @@ err_ns: perf_detach_cgroup(event); if (event->ns) put_pid_ns(event->ns); + if (event->hw.target) + put_task_struct(event->hw.target); kfree(event); return ERR_PTR(err); -- cgit v1.2.3-59-g8ed1b From 5da13ab8b0dcaa984c45ae43edf5a4d148603d42 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 9 Apr 2018 21:16:54 +0900 Subject: perf/core: Fix perf_kprobe_init() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix error handling in perf_kprobe_init(): ================================================================== BUG: KASAN: slab-out-of-bounds in strlen+0x8e/0xa0 lib/string.c:482 Read of size 1 at addr ffff88003f9cc5c0 by task syz-executor2/23095 CPU: 0 PID: 23095 Comm: syz-executor2 Not tainted 4.16.0+ #24 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xca/0x13e lib/dump_stack.c:113 print_address_description+0x6e/0x2c0 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x256/0x380 mm/kasan/report.c:412 strlen+0x8e/0xa0 lib/string.c:482 kstrdup+0x21/0x70 mm/util.c:55 alloc_trace_kprobe+0xc8/0x930 kernel/trace/trace_kprobe.c:325 create_local_trace_kprobe+0x4f/0x3a0 kernel/trace/trace_kprobe.c:1438 perf_kprobe_init+0x149/0x1f0 kernel/trace/trace_event_perf.c:264 perf_kprobe_event_init+0xa8/0x120 kernel/events/core.c:8407 perf_try_init_event+0xcb/0x2a0 kernel/events/core.c:9719 perf_init_event kernel/events/core.c:9750 [inline] perf_event_alloc+0x1367/0x1e20 kernel/events/core.c:10022 SYSC_perf_event_open+0x242/0x2330 kernel/events/core.c:10477 do_syscall_64+0x198/0x640 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Reported-by: 范龙飞 Signed-off-by: Masami Hiramatsu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Song Liu Cc: Thomas Gleixner Fixes: e12f03d7031a ("perf/core: Implement the 'perf_kprobe' PMU") Signed-off-by: Ingo Molnar --- kernel/trace/trace_event_perf.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 2c416509b834..94600f1f7efa 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -252,6 +252,8 @@ int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe) ret = strncpy_from_user( func, u64_to_user_ptr(p_event->attr.kprobe_func), KSYM_NAME_LEN); + if (ret == KSYM_NAME_LEN) + ret = -E2BIG; if (ret < 0) goto out; -- cgit v1.2.3-59-g8ed1b From 0eadcc7a7bc03e991d2da1cf88143fb7cc0342c1 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 9 Apr 2018 18:31:30 +0000 Subject: perf/core: Fix perf_uprobe_init() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Similarly to the uprobe PMU fix in perf_kprobe_init(), fix error handling in perf_uprobe_init() as well. Reported-by: 范龙飞 Signed-off-by: Song Liu Acked-by: Masami Hiramatsu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: e12f03d7031a ("perf/core: Implement the 'perf_kprobe' PMU") Signed-off-by: Ingo Molnar --- kernel/trace/trace_event_perf.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 94600f1f7efa..c79193e598f5 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -302,6 +302,8 @@ int perf_uprobe_init(struct perf_event *p_event, bool is_retprobe) return -ENOMEM; ret = strncpy_from_user( path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX); + if (ret == PATH_MAX) + return -E2BIG; if (ret < 0) goto out; if (path[0] == '\0') { -- cgit v1.2.3-59-g8ed1b From 50268a3d266ecfdd6c5873d62b2758d9732fc598 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Tue, 10 Apr 2018 21:20:08 +0900 Subject: tracing/uprobe_event: Fix strncpy corner case MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix string fetch function to terminate with NUL. It is OK to drop the rest of string. Signed-off-by: Masami Hiramatsu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Song Liu Cc: Thomas Gleixner Cc: security@kernel.org Cc: 范龙飞 Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes") Signed-off-by: Ingo Molnar --- kernel/trace/trace_uprobe.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 2014f4351ae0..0d450b40988e 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -151,6 +151,8 @@ static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs, return; ret = strncpy_from_user(dst, src, maxlen); + if (ret == maxlen) + dst[--ret] = '\0'; if (ret < 0) { /* Failed to fetch string */ ((u8 *)get_rloc_data(dest))[0] = '\0'; -- cgit v1.2.3-59-g8ed1b From 32e6e967fb36bf77ed99221ae3ce1909f045d8f9 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 11 Apr 2018 18:02:37 +0000 Subject: perf/core: Need CAP_SYS_ADMIN to create k/uprobe with perf_event_open() Non-root user cannot create kprobe or uprobe through the text-based interface (kprobe_events, uprobe_events),so they should not be able to create probes via perf_event_open() either. Reported-by: Vince Weaver Signed-off-by: Song Liu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 33ea4b24277b ("perf/core: Implement the 'perf_uprobe' PMU") Fixes: e12f03d7031a ("perf/core: Implement the 'perf_kprobe' PMU") Link: http://lkml.kernel.org/r/C0B2EFB5-C403-4BDB-9046-C14B3EE66999@fb.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index d7af82827373..2d5fe26551f8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8400,6 +8400,10 @@ static int perf_kprobe_event_init(struct perf_event *event) if (event->attr.type != perf_kprobe.type) return -ENOENT; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + /* * no branch sampling for probe events */ @@ -8437,6 +8441,10 @@ static int perf_uprobe_event_init(struct perf_event *event) if (event->attr.type != perf_uprobe.type) return -ENOENT; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + /* * no branch sampling for probe events */ -- cgit v1.2.3-59-g8ed1b