[DTrace-devel] [PATCH v2] options: check *frames option values against system limit
Eugene Loh
eugene.loh at oracle.com
Fri Oct 3 02:05:23 UTC 2025
Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
On 10/2/25 15:09, Kris Van Hees via DTrace-devel wrote:
> Commit 81e99397d ("Add support for the stack() action") added code to
> retrieve the system limit for stack traces and used that value to set
> the 'maxframes' option.
>
> However, a user can set the 'maxframes' option from the command line,
> which would allow setting the option to value beyond the system limit.
>
> We now record the system limit in dtrace_hdl_t as well as setting the
> 'maxframes' option to this value as a default. Options processing now
> ensures that *frames options cannot be set beyond the system limit.
>
> Note: If 'stackframes', 'ustackframes', or 'jstackframes' are set
> before 'maxframes' they could be given a value that exceeds 'maxframes'.
> The existing immplementation in the code generator already lowers their
> value to 'maxframes' as needed.
>
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
> libdtrace/dt_impl.h | 1 +
> libdtrace/dt_open.c | 7 +++-
> libdtrace/dt_options.c | 38 +++++--------------
> .../options/err.jstackframes-negative.d | 24 ++++++++++++
> .../options/err.jstackframes-too-high.sh | 25 ++++++++++++
> .../unittest/options/err.maxframes-negative.d | 24 ++++++++++++
> .../options/err.maxframes-too-high.sh | 25 ++++++++++++
> .../options/err.stackframes-negative.d | 24 ++++++++++++
> .../options/err.stackframes-too-high.sh | 25 ++++++++++++
> .../options/err.ustackframes-negative.d | 24 ++++++++++++
> .../options/err.ustackframes-too-high.sh | 25 ++++++++++++
> 11 files changed, 211 insertions(+), 31 deletions(-)
> create mode 100644 test/unittest/options/err.jstackframes-negative.d
> create mode 100755 test/unittest/options/err.jstackframes-too-high.sh
> create mode 100644 test/unittest/options/err.maxframes-negative.d
> create mode 100755 test/unittest/options/err.maxframes-too-high.sh
> create mode 100644 test/unittest/options/err.stackframes-negative.d
> create mode 100755 test/unittest/options/err.stackframes-too-high.sh
> create mode 100644 test/unittest/options/err.ustackframes-negative.d
> create mode 100755 test/unittest/options/err.ustackframes-too-high.sh
>
> diff --git a/libdtrace/dt_impl.h b/libdtrace/dt_impl.h
> index 4dc4c9a7..723aac8b 100644
> --- a/libdtrace/dt_impl.h
> +++ b/libdtrace/dt_impl.h
> @@ -310,6 +310,7 @@ struct dtrace_hdl {
> uint_t dt_maxtuplesize; /* largest tuple across programs */
> uint_t dt_maxlvaralloc; /* largest lvar alloc across pcbs */
> uint_t dt_maxaggdsize; /* largest aggregation data size */
> + uint64_t dt_maxframes; /* system limit on stack traces */
> dt_tstring_t *dt_tstrings; /* temporary string slots */
> dt_list_t dt_modlist; /* linked list of dt_module_t's */
> dt_htab_t *dt_mods; /* hash table of dt_module_t's */
> diff --git a/libdtrace/dt_open.c b/libdtrace/dt_open.c
> index ed0b14a1..ba5463a0 100644
> --- a/libdtrace/dt_open.c
> +++ b/libdtrace/dt_open.c
> @@ -764,13 +764,16 @@ dt_vopen(int version, int flags, int *errp,
> dtp->dt_options[DTRACEOPT_SCRATCHSIZE] = sizeof(uint64_t) + _dtrace_scratchsize;
>
> /*
> - * Set the default value of maxframes.
> + * Set the default value of maxframes. This is the maximum of stack
> + * frames that can be requested from the kernel. The *frames options
> + * cannot be set to a value that exceeds this limit.
> */
> fd = fopen("/proc/sys/kernel/perf_event_max_stack", "r");
> assert(fd);
> - if (fscanf(fd, "%lu", &dtp->dt_options[DTRACEOPT_MAXFRAMES]) != 1)
> + if (fscanf(fd, "%lu", &dtp->dt_maxframes) != 1)
> return set_open_errno(dtp, errp, EDT_READMAXSTACK);
> fclose(fd);
> + dtp->dt_options[DTRACEOPT_MAXFRAMES] = dtp->dt_maxframes;
>
> /*
> * Set the default pcap capture size.
> diff --git a/libdtrace/dt_options.c b/libdtrace/dt_options.c
> index 7508f044..97516517 100644
> --- a/libdtrace/dt_options.c
> +++ b/libdtrace/dt_options.c
> @@ -913,40 +913,20 @@ dt_opt_rate(dtrace_hdl_t *dtp, const char *arg, uintptr_t option)
> }
>
> /*
> - * When setting the maxframes option, set the option in the dt_options array
> - * using dt_opt_runtime() as usual, and then update the definition of the CTF
> - * type for "_stack" to be an array of the corresponding size.
> - * If any errors occur, reset dt_options[option] to its previous value.
> + * Set a *frames option, ensuring that its value is within the system
> + * constaints.
> */
> static int
> -dt_opt_maxframes(dtrace_hdl_t *dtp, const char *arg, uintptr_t option)
> +dt_opt_frames(dtrace_hdl_t *dtp, const char *arg, uintptr_t option)
> {
> dtrace_optval_t val = dtp->dt_options[option];
> - ctf_file_t *fp = DT_STACK_CTFP(dtp);
> - ctf_id_t type = ctf_type_resolve(fp, DT_STACK_TYPE(dtp));
> - ctf_arinfo_t r;
>
> if (dt_opt_runtime(dtp, arg, option) != 0)
> return -1; /* dt_errno is set for us */
>
> - if (dtp->dt_options[option] > UINT_MAX) {
> - dtp->dt_options[option] = val;
> - return dt_set_errno(dtp, EOVERFLOW);
> - }
> -
> - if (ctf_array_info(fp, type, &r) == CTF_ERR) {
> - dtp->dt_options[option] = val;
> - dtp->dt_ctferr = ctf_errno(fp);
> - return dt_set_errno(dtp, EDT_CTF);
> - }
> -
> - r.ctr_nelems = (uint_t)dtp->dt_options[option];
> -
> - if (ctf_set_array(fp, type, &r) == CTF_ERR ||
> - ctf_update(fp) == CTF_ERR) {
> + if (dtp->dt_options[option] > dtp->dt_maxframes) {
> dtp->dt_options[option] = val;
> - dtp->dt_ctferr = ctf_errno(fp);
> - return dt_set_errno(dtp, EDT_CTF);
> + return dt_set_errno(dtp, EDT_BADOPTVAL);
> }
>
> return 0;
> @@ -1194,19 +1174,19 @@ static const dt_option_t _dtrace_rtoptions[] = {
> { "destructive", dt_opt_runtime, DTRACEOPT_DESTRUCTIVE },
> { "dynvarsize", dt_opt_size, DTRACEOPT_DYNVARSIZE },
> { "grabanon", dt_opt_runtime, DTRACEOPT_GRABANON },
> - { "jstackframes", dt_opt_runtime, DTRACEOPT_JSTACKFRAMES },
> + { "jstackframes", dt_opt_frames, DTRACEOPT_JSTACKFRAMES },
> { "jstackstrsize", dt_opt_size, DTRACEOPT_JSTACKSTRSIZE },
> { "lockmem", dt_opt_lockmem, DTRACEOPT_LOCKMEM },
> - { "maxframes", dt_opt_maxframes, DTRACEOPT_MAXFRAMES },
> + { "maxframes", dt_opt_frames, DTRACEOPT_MAXFRAMES },
> { "nusdtprobes", dt_opt_runtime, DTRACEOPT_NUSDTPROBES },
> { "nspec", dt_opt_runtime, DTRACEOPT_NSPEC },
> { "pcapsize", dt_opt_pcapsize, DTRACEOPT_PCAPSIZE },
> { "scratchsize", dt_opt_scratchsize, DTRACEOPT_SCRATCHSIZE },
> { "specsize", dt_opt_size, DTRACEOPT_SPECSIZE },
> - { "stackframes", dt_opt_runtime, DTRACEOPT_STACKFRAMES },
> + { "stackframes", dt_opt_frames, DTRACEOPT_STACKFRAMES },
> { "statusrate", dt_opt_rate, DTRACEOPT_STATUSRATE },
> { "strsize", dt_opt_strsize, DTRACEOPT_STRSIZE },
> - { "ustackframes", dt_opt_runtime, DTRACEOPT_USTACKFRAMES },
> + { "ustackframes", dt_opt_frames, DTRACEOPT_USTACKFRAMES },
> { "noresolve", dt_opt_runtime, DTRACEOPT_NORESOLVE },
> { NULL }
> };
> diff --git a/test/unittest/options/err.jstackframes-negative.d b/test/unittest/options/err.jstackframes-negative.d
> new file mode 100644
> index 00000000..0fdcbb58
> --- /dev/null
> +++ b/test/unittest/options/err.jstackframes-negative.d
> @@ -0,0 +1,24 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: The -xjstackframes option requires a non-negative value
> + *
> + * SECTION: Options and Tunables/Consumer Options
> + */
> +
> +/* @@runtest-opts: -xjstackframes=-1 */
> +
> +BEGIN
> +{
> + exit(0);
> +}
> +
> +ERROR
> +{
> + exit(1);
> +}
> diff --git a/test/unittest/options/err.jstackframes-too-high.sh b/test/unittest/options/err.jstackframes-too-high.sh
> new file mode 100755
> index 00000000..869a3d1f
> --- /dev/null
> +++ b/test/unittest/options/err.jstackframes-too-high.sh
> @@ -0,0 +1,25 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +
> +#
> +# ASSERTION: The -xjstackframes option value must be within the system limit.
> +#
> +# SECTION: Options and Tunables/Consumer Options
> +#
> +maxframes=$[ `cat /proc/sys/kernel/perf_event_max_stack` + 1 ]
> +
> +$dtrace $dt_flags -xjstackframes=$maxframes -qn '
> +BEGIN, ERROR
> +{
> + trace("ERROR: DTrace should fail to start.");
> + exit(0);
> +}'
> +
> +exit $?
> diff --git a/test/unittest/options/err.maxframes-negative.d b/test/unittest/options/err.maxframes-negative.d
> new file mode 100644
> index 00000000..62e4d21f
> --- /dev/null
> +++ b/test/unittest/options/err.maxframes-negative.d
> @@ -0,0 +1,24 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: The -xmaxframes option requires a non-negative value
> + *
> + * SECTION: Options and Tunables/Consumer Options
> + */
> +
> +/* @@runtest-opts: -xmaxframes=-1 */
> +
> +BEGIN
> +{
> + exit(0);
> +}
> +
> +ERROR
> +{
> + exit(1);
> +}
> diff --git a/test/unittest/options/err.maxframes-too-high.sh b/test/unittest/options/err.maxframes-too-high.sh
> new file mode 100755
> index 00000000..3b2674cf
> --- /dev/null
> +++ b/test/unittest/options/err.maxframes-too-high.sh
> @@ -0,0 +1,25 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +
> +#
> +# ASSERTION: The -xmaxframes option value must be within the system limit.
> +#
> +# SECTION: Options and Tunables/Consumer Options
> +#
> +maxframes=$[ `cat /proc/sys/kernel/perf_event_max_stack` + 1 ]
> +
> +$dtrace $dt_flags -xmaxframes=$maxframes -qn '
> +BEGIN, ERROR
> +{
> + trace("ERROR: DTrace should fail to start.");
> + exit(0);
> +}'
> +
> +exit $?
> diff --git a/test/unittest/options/err.stackframes-negative.d b/test/unittest/options/err.stackframes-negative.d
> new file mode 100644
> index 00000000..e6c276d7
> --- /dev/null
> +++ b/test/unittest/options/err.stackframes-negative.d
> @@ -0,0 +1,24 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: The -xstackframes option requires a non-negative value
> + *
> + * SECTION: Options and Tunables/Consumer Options
> + */
> +
> +/* @@runtest-opts: -xstackframes=-1 */
> +
> +BEGIN
> +{
> + exit(0);
> +}
> +
> +ERROR
> +{
> + exit(1);
> +}
> diff --git a/test/unittest/options/err.stackframes-too-high.sh b/test/unittest/options/err.stackframes-too-high.sh
> new file mode 100755
> index 00000000..0123f92b
> --- /dev/null
> +++ b/test/unittest/options/err.stackframes-too-high.sh
> @@ -0,0 +1,25 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +
> +#
> +# ASSERTION: The -xstackframes option value must be within the system limit.
> +#
> +# SECTION: Options and Tunables/Consumer Options
> +#
> +maxframes=$[ `cat /proc/sys/kernel/perf_event_max_stack` + 1 ]
> +
> +$dtrace $dt_flags -xstackframes=$maxframes -qn '
> +BEGIN, ERROR
> +{
> + trace("ERROR: DTrace should fail to start.");
> + exit(0);
> +}'
> +
> +exit $?
> diff --git a/test/unittest/options/err.ustackframes-negative.d b/test/unittest/options/err.ustackframes-negative.d
> new file mode 100644
> index 00000000..ede20425
> --- /dev/null
> +++ b/test/unittest/options/err.ustackframes-negative.d
> @@ -0,0 +1,24 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION: The -xustackframes option requires a non-negative value
> + *
> + * SECTION: Options and Tunables/Consumer Options
> + */
> +
> +/* @@runtest-opts: -xustackframes=-1 */
> +
> +BEGIN
> +{
> + exit(0);
> +}
> +
> +ERROR
> +{
> + exit(1);
> +}
> diff --git a/test/unittest/options/err.ustackframes-too-high.sh b/test/unittest/options/err.ustackframes-too-high.sh
> new file mode 100755
> index 00000000..fc362fff
> --- /dev/null
> +++ b/test/unittest/options/err.ustackframes-too-high.sh
> @@ -0,0 +1,25 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +
> +#
> +# ASSERTION: The -xustackframes option value must be within the system limit.
> +#
> +# SECTION: Options and Tunables/Consumer Options
> +#
> +maxframes=$[ `cat /proc/sys/kernel/perf_event_max_stack` + 1 ]
> +
> +$dtrace $dt_flags -xustackframes=$maxframes -qn '
> +BEGIN, ERROR
> +{
> + trace("ERROR: DTrace should fail to start.");
> + exit(0);
> +}'
> +
> +exit $?
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