diff options
| author | Johannes Weiner <hannes@cmpxchg.org> | 2016-11-22 10:57:42 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-22 12:36:58 +0100 |
| commit | ae31fe51a3cceaa0cabdb3058f69669ecb47f12e (patch) | |
| tree | a7d81be30bb3f88188e483748b360f4237a39f8a /arch | |
| parent | e96271f3ed7e702fa36dd0605c0c5b5f065af816 (diff) | |
perf/x86: Restore TASK_SIZE check on frame pointer
The following commit:
75925e1ad7f5 ("perf/x86: Optimize stack walk user accesses")
... switched from copy_from_user_nmi() to __copy_from_user_nmi() with a manual
access_ok() check.
Unfortunately, copy_from_user_nmi() does an explicit check against TASK_SIZE,
whereas the access_ok() uses whatever the current address limit of the task is.
We are getting NMIs when __probe_kernel_read() has switched to KERNEL_DS, and
then see vmalloc faults when we access what looks like pointers into vmalloc
space:
[] WARNING: CPU: 3 PID: 3685731 at arch/x86/mm/fault.c:435 vmalloc_fault+0x289/0x290
[] CPU: 3 PID: 3685731 Comm: sh Tainted: G W 4.6.0-5_fbk1_223_gdbf0f40 #1
[] Call Trace:
[] <NMI> [<ffffffff814717d1>] dump_stack+0x4d/0x6c
[] [<ffffffff81076e43>] __warn+0xd3/0xf0
[] [<ffffffff81076f2d>] warn_slowpath_null+0x1d/0x20
[] [<ffffffff8104a899>] vmalloc_fault+0x289/0x290
[] [<ffffffff8104b5a0>] __do_page_fault+0x330/0x490
[] [<ffffffff8104b70c>] do_page_fault+0xc/0x10
[] [<ffffffff81794e82>] page_fault+0x22/0x30
[] [<ffffffff81006280>] ? perf_callchain_user+0x100/0x2a0
[] [<ffffffff8115124f>] get_perf_callchain+0x17f/0x190
[] [<ffffffff811512c7>] perf_callchain+0x67/0x80
[] [<ffffffff8114e750>] perf_prepare_sample+0x2a0/0x370
[] [<ffffffff8114e840>] perf_event_output+0x20/0x60
[] [<ffffffff8114aee7>] ? perf_event_update_userpage+0xc7/0x130
[] [<ffffffff8114ea01>] __perf_event_overflow+0x181/0x1d0
[] [<ffffffff8114f484>] perf_event_overflow+0x14/0x20
[] [<ffffffff8100a6e3>] intel_pmu_handle_irq+0x1d3/0x490
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] [<ffffffff81197191>] ? vunmap_page_range+0x1a1/0x2f0
[] [<ffffffff811972f1>] ? unmap_kernel_range_noflush+0x11/0x20
[] [<ffffffff814f2056>] ? ghes_copy_tofrom_phys+0x116/0x1f0
[] [<ffffffff81040d1d>] ? x2apic_send_IPI_self+0x1d/0x20
[] [<ffffffff8100411d>] perf_event_nmi_handler+0x2d/0x50
[] [<ffffffff8101ea31>] nmi_handle+0x61/0x110
[] [<ffffffff8101ef94>] default_do_nmi+0x44/0x110
[] [<ffffffff8101f13b>] do_nmi+0xdb/0x150
[] [<ffffffff81795187>] end_repeat_nmi+0x1a/0x1e
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] [<ffffffff8147daf7>] ? copy_user_enhanced_fast_string+0x7/0x10
[] <<EOE>> <IRQ> [<ffffffff8115d05e>] ? __probe_kernel_read+0x3e/0xa0
Fix this by moving the valid_user_frame() check to before the uaccess
that loads the return address and the pointer to the next frame.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Fixes: 75925e1ad7f5 ("perf/x86: Optimize stack walk user accesses")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/events/core.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index d31735f37ed7..9d4bf3ab049e 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2352,7 +2352,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent frame.next_frame = 0; frame.return_address = 0; - if (!access_ok(VERIFY_READ, fp, 8)) + if (!valid_user_frame(fp, sizeof(frame))) break; bytes = __copy_from_user_nmi(&frame.next_frame, fp, 4); @@ -2362,9 +2362,6 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent if (bytes != 0) break; - if (!valid_user_frame(fp, sizeof(frame))) - break; - perf_callchain_store(entry, cs_base + frame.return_address); fp = compat_ptr(ss_base + frame.next_frame); } @@ -2413,7 +2410,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs frame.next_frame = NULL; frame.return_address = 0; - if (!access_ok(VERIFY_READ, fp, sizeof(*fp) * 2)) + if (!valid_user_frame(fp, sizeof(frame))) break; bytes = __copy_from_user_nmi(&frame.next_frame, fp, sizeof(*fp)); @@ -2423,9 +2420,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs if (bytes != 0) break; - if (!valid_user_frame(fp, sizeof(frame))) - break; - perf_callchain_store(entry, frame.return_address); fp = (void __user *)frame.next_frame; } |