linux-stable.git/kernel/trace/trace_uprobe.c, branch v3.18.136

tracing/uprobes: Fix output for multiple string arguments

2019-02-20T09:09:11+00:00

commit 0722069a5374b904ec1a67f91249f90e1cfae259 upstream.

When printing multiple uprobe arguments as strings the output for the
earlier arguments would also include all later string arguments.

This is best explained in an example:

Consider adding a uprobe to a function receiving two strings as
parameters which is at offset 0xa0 in strlib.so and we want to print
both parameters when the uprobe is hit (on x86_64):

$ echo 'p:func /lib/strlib.so:0xa0 +0(%di):string +0(%si):string' > \
    /sys/kernel/debug/tracing/uprobe_events

When the function is called as func("foo", "bar") and we hit the probe,
the trace file shows a line like the following:

  [...] func: (0x7f7e683706a0) arg1="foobar" arg2="bar"

Note the extra "bar" printed as part of arg1. This behaviour stacks up
for additional string arguments.

The strings are stored in a dynamically growing part of the uprobe
buffer by fetch_store_string() after copying them from userspace via
strncpy_from_user(). The return value of strncpy_from_user() is then
directly used as the required size for the string. However, this does
not take the terminating null byte into account as the documentation
for strncpy_from_user() cleary states that it "[...] returns the
length of the string (not including the trailing NUL)" even though the
null byte will be copied to the destination.

Therefore, subsequent calls to fetch_store_string() will overwrite
the terminating null byte of the most recently fetched string with
the first character of the current string, leading to the
"accumulation" of strings in earlier arguments in the output.

Fix this by incrementing the return value of strncpy_from_user() by
one if we did not hit the maximum buffer size.

Link: http://lkml.kernel.org/r/20190116141629.5752-1-andreas.ziegler@fau.de

Cc: Ingo Molnar 
Cc: stable@vger.kernel.org
Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes")
Acked-by: Masami Hiramatsu 
Signed-off-by: Andreas Ziegler 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Greg Kroah-Hartman

uprobes: Use synchronize_rcu() not synchronize_sched()

2018-09-09T18:07:55+00:00

commit 016f8ffc48cb01d1e7701649c728c5d2e737d295 upstream.

While debugging another bug, I was looking at all the synchronize*()
functions being used in kernel/trace, and noticed that trace_uprobes was
using synchronize_sched(), with a comment to synchronize with
{u,ret}_probe_trace_func(). When looking at those functions, the data is
protected with "rcu_read_lock()" and not with "rcu_read_lock_sched()". This
is using the wrong synchronize_*() function.

Link: http://lkml.kernel.org/r/20180809160553.469e1e32@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: 70ed91c6ec7f8 ("tracing/uprobes: Support ftrace_event_file base multibuffer")
Acked-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing/uprobe_event: Fix strncpy corner case

2018-05-16T08:05:18+00:00

commit 50268a3d266ecfdd6c5873d62b2758d9732fc598 upstream.

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 
Signed-off-by: Greg Kroah-Hartman

perf: Avoid horrible stack usage

2017-04-30T03:49:15+00:00

commit 86038c5ea81b519a8a1fcfcd5e4599aab0cdd119 upstream.

Both Linus (most recent) and Steve (a while ago) reported that perf
related callbacks have massive stack bloat.

The problem is that software events need a pt_regs in order to
properly report the event location and unwind stack. And because we
could not assume one was present we allocated one on stack and filled
it with minimal bits required for operation.

Now, pt_regs is quite large, so this is undesirable. Furthermore it
turns out that most sites actually have a pt_regs pointer available,
making this even more onerous, as the stack space is pointless waste.

This patch addresses the problem by observing that software events
have well defined nesting semantics, therefore we can use static
per-cpu storage instead of on-stack.

Linus made the further observation that all but the scheduler callers
of perf_sw_event() have a pt_regs available, so we change the regular
perf_sw_event() to require a valid pt_regs (where it used to be
optional) and add perf_sw_event_sched() for the scheduler.

We have a scheduler specific call instead of a more generic _noregs()
like construct because we can assume non-recursion from the scheduler
and thereby simplify the code further (_noregs would have to put the
recursion context call inline in order to assertain which __perf_regs
element to use).

One last note on the implementation of perf_trace_buf_prepare(); we
allow .regs = NULL for those cases where we already have a pt_regs
pointer available and do not need another.

Reported-by: Linus Torvalds 
Reported-by: Steven Rostedt 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Javi Merino 
Cc: Linus Torvalds 
Cc: Mathieu Desnoyers 
Cc: Oleg Nesterov 
Cc: Paul Mackerras 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: Tom Zanussi 
Cc: Vaibhav Nagarnaik 
Link: http://lkml.kernel.org/r/20141216115041.GW3337@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar 
Cc: Arnd Bergmann 
Signed-off-by: Greg Kroah-Hartman

tracing/uprobes: Kill the dead TRACE_EVENT_FL_USE_CALL_FILTER logic

2014-07-16T18:25:19+00:00

alloc_trace_uprobe() sets TRACE_EVENT_FL_USE_CALL_FILTER for unknown
reason and this is simply wrong. Fortunately this has no effect because
register_uprobe_event() clears call->flags after that.

Kill both. This trace_uprobe was kzalloc'ed and we rely on this fact
anyway.

Link: http://lkml.kernel.org/p/20140715184824.GA20505@redhat.com

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Signed-off-by: Steven Rostedt

tracing/uprobes: Fix the usage of uprobe_buffer_enable() in probe_event_enable()

2014-06-30T17:22:33+00:00

The usage of uprobe_buffer_enable() added by dcad1a20 is very wrong,

1. uprobe_buffer_enable() and uprobe_buffer_disable() are not balanced,
   _enable() should be called only if !enabled.

2. If uprobe_buffer_enable() fails probe_event_enable() should clear
   tp.flags and free event_file_link.

3. If uprobe_register() fails it should do uprobe_buffer_disable().

Link: http://lkml.kernel.org/p/20140627170146.GA18332@redhat.com

Acked-by: Namhyung Kim 
Acked-by: Srikar Dronamraju 
Reviewed-by: Masami Hiramatsu 
Fixes: dcad1a204f72 "tracing/uprobes: Fetch args before reserving a ring buffer"
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

tracing/uprobes: Kill the bogus UPROBE_HANDLER_REMOVE code in uprobe_dispatcher()

2014-06-30T17:22:23+00:00

I do not know why dd9fa555d7bb "tracing/uprobes: Move argument fetching
to uprobe_dispatcher()" added the UPROBE_HANDLER_REMOVE, but it looks
wrong.

OK, perhaps it makes sense to avoid store_trace_args() if the tracee is
nacked by uprobe_perf_filter(). But then we should kill the same code
in uprobe_perf_func() and unify the TRACE/PROFILE filtering (we need to
do this anyway to mix perf/ftrace). Until then this code actually adds
the pessimization because uprobe_perf_filter() will be called twice and
return T in likely case.

Link: http://lkml.kernel.org/p/20140627170143.GA18329@redhat.com

Acked-by: Namhyung Kim 
Acked-by: Srikar Dronamraju 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

tracing/uprobes: Revert "Support mix of ftrace and perf"

2014-06-30T17:21:58+00:00

This reverts commit 43fe98913c9f67e3b523615ee3316f9520a623e0.

This patch is very wrong. Firstly, this change leads to unbalanced
uprobe_unregister(). Just for example,

	# perf probe -x /lib/libc.so.6 syscall
	# echo 1 >> /sys/kernel/debug/tracing/events/probe_libc/enable
	# perf record -e probe_libc:syscall whatever

after that uprobe is dead (unregistered) but the user of ftrace/perf
can't know this, and it looks as if nobody hits this probe.

This would be easy to fix, but there are other reasons why it is not
simple to mix ftrace and perf. If nothing else, they can't share the
same ->consumer.filter. This is fixable too, but probably we need to
fix the poorly designed uprobe_register() interface first. At least
"register" and "apply" should be clearly separated.

Link: http://lkml.kernel.org/p/20140627170136.GA18319@redhat.com

Cc: Tom Zanussi 
Cc: "zhangwei(Jovi)" 
Cc: stable@vger.kernel.org # v3.14
Acked-by: Namhyung Kim 
Acked-by: Srikar Dronamraju 
Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt

Merge branch 'perf/kprobes' into perf/core

2014-06-05T10:26:50+00:00

Conflicts:
	arch/x86/kernel/traps.c

The kprobes enhancements are fully cooked, ship them upstream.

Signed-off-by: Ingo Molnar

uprobes/tracing: Fix uprobe_perf_open() on uprobe_apply() failure

2014-04-30T17:10:42+00:00

uprobe_perf_open()->uprobe_apply() can fail, but this error is wrongly
ignored. Change uprobe_perf_open() to do uprobe_perf_close() and return
the error code in this case.

Change uprobe_perf_close() to propogate the error from uprobe_apply()
as well, although it should not fail.

Signed-off-by: Oleg Nesterov 
Acked-by: Steven Rostedt 
Acked-by: Srikar Dronamraju