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Fix NULL pointer access in trace_probe_unlink() by initializing
trace_probe.list correctly in trace_probe_init().
In the error case of trace_probe_init(), it can call trace_probe_unlink()
before initializing trace_probe.list member. This causes NULL pointer
dereference at list_del_init() in trace_probe_unlink().
Syzbot reported :
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: 8633 Comm: syz-executor797 Not tainted 5.3.0-rc8-next-20190915
#0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__list_del_entry_valid+0x85/0xf5 lib/list_debug.c:51
Code: 0f 84 e1 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c4 0f 84 e2 00
00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75
53 49 8b 14 24 4c 39 f2 0f 85 99 00 00 00 49 8d 7d
RSP: 0018:ffff888090a7f9d8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88809b6f90c0 RCX: ffffffff817c0ca9
RDX: 0000000000000000 RSI: ffffffff817c0a73 RDI: ffff88809b6f90c8
RBP: ffff888090a7f9f0 R08: ffff88809a04e600 R09: ffffed1015d26aed
R10: ffffed1015d26aec R11: ffff8880ae935763 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88809b6f90c0 R15: ffff88809b6f90d0
FS: 0000555556f99880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000006cc090 CR3: 00000000962b2000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__list_del_entry include/linux/list.h:131 [inline]
list_del_init include/linux/list.h:190 [inline]
trace_probe_unlink+0x1f/0x200 kernel/trace/trace_probe.c:959
trace_probe_cleanup+0xd3/0x110 kernel/trace/trace_probe.c:973
trace_probe_init+0x3f2/0x510 kernel/trace/trace_probe.c:1011
alloc_trace_uprobe+0x5e/0x250 kernel/trace/trace_uprobe.c:353
create_local_trace_uprobe+0x109/0x4a0 kernel/trace/trace_uprobe.c:1508
perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:314
perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:8898
perf_try_init_event+0x135/0x590 kernel/events/core.c:10184
perf_init_event kernel/events/core.c:10228 [inline]
perf_event_alloc.part.0+0x1b89/0x33d0 kernel/events/core.c:10505
perf_event_alloc kernel/events/core.c:10887 [inline]
__do_sys_perf_event_open+0xa2d/0x2d00 kernel/events/core.c:10989
__se_sys_perf_event_open kernel/events/core.c:10871 [inline]
__x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10871
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Link: http://lkml.kernel.org/r/156869709721.22406.5153754822203046939.stgit@devnote2
Reported-by: syzbot+2f807f4d3a2a4e87f18f@syzkaller.appspotmail.com
Fixes: ca89bc071d5e ("tracing/kprobe: Add multi-probe per event support")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Original changelog from Steve Rostedt (except last sentence which
explains the problem, and the Fixes: tag):
I performed a three way histogram with the following commands:
echo 'irq_lat u64 lat pid_t pid' > synthetic_events
echo 'wake_lat u64 lat u64 irqlat pid_t pid' >> synthetic_events
echo 'hist:keys=common_pid:irqts=common_timestamp.usecs if function == 0xffffffff81200580' > events/timer/hrtimer_start/trigger
echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$irqts:onmatch(timer.hrtimer_start).irq_lat($lat,pid) if common_flags & 1' > events/sched/sched_waking/trigger
echo 'hist:keys=pid:wakets=common_timestamp.usecs,irqlat=lat' > events/synthetic/irq_lat/trigger
echo 'hist:keys=next_pid:lat=common_timestamp.usecs-$wakets,irqlat=$irqlat:onmatch(synthetic.irq_lat).wake_lat($lat,$irqlat,next_pid)' > events/sched/sched_switch/trigger
echo 1 > events/synthetic/wake_lat/enable
Basically I wanted to see:
hrtimer_start (calling function tick_sched_timer)
Note:
# grep tick_sched_timer /proc/kallsyms
ffffffff81200580 t tick_sched_timer
And save the time of that, and then record sched_waking if it is called
in interrupt context and with the same pid as the hrtimer_start, it
will record the latency between that and the waking event.
I then look at when the task that is woken is scheduled in, and record
the latency between the wakeup and the task running.
At the end, the wake_lat synthetic event will show the wakeup to
scheduled latency, as well as the irq latency in from hritmer_start to
the wakeup. The problem is that I found this:
<idle>-0 [007] d... 190.485261: wake_lat: lat=27 irqlat=190485230 pid=698
<idle>-0 [005] d... 190.485283: wake_lat: lat=40 irqlat=190485239 pid=10
<idle>-0 [002] d... 190.488327: wake_lat: lat=56 irqlat=190488266 pid=335
<idle>-0 [005] d... 190.489330: wake_lat: lat=64 irqlat=190489262 pid=10
<idle>-0 [003] d... 190.490312: wake_lat: lat=43 irqlat=190490265 pid=77
<idle>-0 [005] d... 190.493322: wake_lat: lat=54 irqlat=190493262 pid=10
<idle>-0 [005] d... 190.497305: wake_lat: lat=35 irqlat=190497267 pid=10
<idle>-0 [005] d... 190.501319: wake_lat: lat=50 irqlat=190501264 pid=10
The irqlat seemed quite large! Investigating this further, if I had
enabled the irq_lat synthetic event, I noticed this:
<idle>-0 [002] d.s. 249.429308: irq_lat: lat=164968 pid=335
<idle>-0 [002] d... 249.429369: wake_lat: lat=55 irqlat=249429308 pid=335
Notice that the timestamp of the irq_lat "249.429308" is awfully
similar to the reported irqlat variable. In fact, all instances were
like this. It appeared that:
irqlat=$irqlat
Wasn't assigning the old $irqlat to the new irqlat variable, but
instead was assigning the $irqts to it.
The issue is that assigning the old $irqlat to the new irqlat variable
creates a variable reference alias, but the alias creation code
forgets to make sure the alias uses the same var_ref_idx to access the
reference.
Link: http://lkml.kernel.org/r/1567375321.5282.12.camel@kernel.org
Cc: Linux Trace Devel <linux-trace-devel@vger.kernel.org>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: 7e8b88a30b085 ("tracing: Add hist trigger support for variable reference aliases")
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Hex dump as many as 16 bytes at once in trace_print_hex_seq()
instead of byte-by-byte approach.
Link: http://lkml.kernel.org/r/20190806151543.86061-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Function ftrace_lookup_ip() will check empty hash table. So we don't
need extra check outside.
Link: http://lkml.kernel.org/r/20190910143336.13472-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add "gfp_t" support in synthetic_events, then the "gfp_t" type
parameter in some functions can be traced.
Prints the gfp flags as hex in addition to the human-readable flag
string. Example output:
whoopsie-630 [000] ...1 78.969452: testevent: bar=b20 (GFP_ATOMIC|__GFP_ZERO)
rcuc/0-11 [000] ...1 81.097555: testevent: bar=a20 (GFP_ATOMIC)
rcuc/0-11 [000] ...1 81.583123: testevent: bar=a20 (GFP_ATOMIC)
Link: http://lkml.kernel.org/r/20190712015308.9908-1-zhengjun.xing@linux.intel.com
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
[ Added printing of flag names ]
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The name tracing_reset() was a misnomer, as it really only reset a single
CPU buffer. Rename it to tracing_reset_cpu() and also make it static and
remove the prototype from trace.h, as it is only used in a single function.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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As the max stack tracer algorithm is not that easy to understand from the
code, add comments that explain the algorithm and mentions how
ARCH_FTRACE_SHIFT_STACK_TRACER affects it.
Link: http://lkml.kernel.org/r/20190806123455.487ac02b@gandalf.local.home
Suggested-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Most archs (well at least x86) store the function call return address on the
stack before storing the local variables for the function. The max stack
tracer depends on this in its algorithm to display the stack size of each
function it finds in the back trace.
Some archs (arm64), may store the return address (from its link register)
just before calling a nested function. There's no reason to save the link
register on leaf functions, as it wont be updated. This breaks the algorithm
of the max stack tracer.
Add a new define ARCH_FTRACE_SHIFT_STACK_TRACER that an architecture may set
if it stores the return address (link register) after it stores the
function's local variables, and have the stack trace shift the values of the
mapped stack size to the appropriate functions.
Link: 20190802094103.163576-1-jiping.ma2@windriver.com
Reported-by: Jiping Ma <jiping.ma2@windriver.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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cleanup() mostly frees/unmaps the malloc'd/privately-mapped
copy of the ELF file recordmcount is working on, which is
set up in mmap_file(). It also deals with positioning within
the pseduo prive-mapping of the file and appending to the ELF
file.
Split into two steps:
mmap_cleanup() for the mapping itself
file_append_cleanup() for allocations storing the
appended ELF data.
Also, move the global variable initializations out of the main,
per-object-file loop and nearer to the alloc/init (mmap_file())
and two cleanup functions so we can more clearly see how they're
related.
Link: http://lkml.kernel.org/r/2a387ac86d133d22c68f57b9933c32bab1d09a2d.1564596289.git.mhelsley@vmware.com
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Redundant cleanup calls were introduced when transitioning from
the old error/success handling via setjmp/longjmp -- the longjmp
ensured the cleanup() call only happened once but replacing
the success_file()/fail_file() calls with cleanup() meant that
multiple cleanup() calls can happen as we return from function
calls.
In do_file(), looking just before and after the "goto out" jumps we
can see that multiple cleanups() are being performed. We remove
cleanup() calls from the nested functions because it makes the code
easier to review -- the resources being cleaned up are generally
allocated and initialized in the callers so freeing them there
makes more sense.
Other redundant cleanup() calls:
mmap_file() is only called from do_file() and, if mmap_file() fails,
then we goto out and do cleanup() there too.
write_file() is only called from do_file() and do_file()
calls cleanup() unconditionally after returning from write_file()
therefore the cleanup() calls in write_file() are not necessary.
find_secsym_ndx(), called from do_func()'s for-loop, when we are
cleaning up here it's obvious that we break out of the loop and
do another cleanup().
__has_rel_mcount() is called from two parts of do_func()
and calls cleanup(). In theory we move them into do_func(), however
these in turn prove redundant so another simplification step
removes them as well.
Link: http://lkml.kernel.org/r/de197e17fc5426623a847ea7cf3a1560a7402a4b.1564596289.git.mhelsley@vmware.com
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Fix up the whitespace irregularity in the ELF switch
blocks.
Swapping the initial value of gpfx allows us to
simplify all but one of the one-line switch cases even
further.
Link: http://lkml.kernel.org/r/647f21f43723d3e831cedd3238c893db03eea6f0.1564596289.git.mhelsley@vmware.com
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The uwrite() and ulseek() functions are formatted inconsistently
with the rest of the file and the kernel overall. While we're
making other changes here let's fix this.
Link: http://lkml.kernel.org/r/4c67698f734be9867a2aba7035fe0ce59e1e4423.1564596289.git.mhelsley@vmware.com
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Recordmcount uses setjmp/longjmp to manage control flow as
it reads and then writes the ELF file. This unusual control
flow is hard to follow and check in addition to being unlike
kernel coding style.
So we rewrite these paths to use regular return values to
indicate error/success. When an error or previously-completed object
file is found we return an error code following kernel
coding conventions -- negative error values and 0 for success when
we're not returning a pointer. We return NULL for those that fail
and return non-NULL pointers otherwise.
One oddity is already_has_rel_mcount -- there we use pointer comparison
rather than string comparison to differentiate between
previously-processed object files and returning the name of a text
section.
Link: http://lkml.kernel.org/r/8ba8633d4afe444931f363c8d924bf9565b89a86.1564596289.git.mhelsley@vmware.com
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add syntax error test cases for multiprobe appending
errors.
Link: http://lkml.kernel.org/r/156095694541.28024.11918630805148623119.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add syntax error test cases for immediate value and
immediate string.
Link: http://lkml.kernel.org/r/156095693553.28024.7730929892585591691.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Masami Hiramatsu
Tom Zanussi
Andy Shevchenko
Changbin Du
Zhengjun Xing
Steven Rostedt (VMware)
Matt Helsley