[DTrace-devel] [PATCH v2] usdt: enforce provider name size limit

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>

On 2/19/26 10:55, Kris Van Hees via DTrace-devel wrote:
> Since USDT provider names have a PID appended to them, the base provider
> name cannot be longer than 53 characters (PID can take up to 10 chars).
>
> This patch also fixes error reporting for linker errors.
>
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>   libdtrace/dt_link.c                     | 24 ++++++++++++---
>   test/unittest/usdt/err.prov-too-long.r  |  3 ++
>   test/unittest/usdt/err.prov-too-long.sh | 41 +++++++++++++++++++++++++
>   3 files changed, 63 insertions(+), 5 deletions(-)
>   create mode 100644 test/unittest/usdt/err.prov-too-long.r
>   create mode 100755 test/unittest/usdt/err.prov-too-long.sh
>
> diff --git a/libdtrace/dt_link.c b/libdtrace/dt_link.c
> index ffa16d9a..6d733881 100644
> --- a/libdtrace/dt_link.c
> +++ b/libdtrace/dt_link.c
> @@ -148,7 +148,15 @@ note_add_provider(usdt_elf_t *usdt, dt_provider_t *pvp)
>   	usdt->base = ALIGN(usdt->base + usdt->size, 4);
>   	usdt->size = 0;
>   
> +	/* Ensure there is enough space in the provider name for the PID. */
>   	len = strlen(pvp->desc.dtvd_name);
> +	if (len > DTRACE_PROVNAMELEN - 11)
> +		return dt_link_error(usdt->dtp, NULL, -1,
> +				     "USDT provider name may not exceed %d "
> +				     "characters: %s\n",
> +				     DTRACE_PROVNAMELEN - 11,
> +				     pvp->desc.dtvd_name);
> +
>   	sz = PROV_NOTE_HEADSZ +
>   	     ALIGN(len + 1, 4) +	/* provider name */
>   	     6 * sizeof(uint32_t);	/* stability attributes */
> @@ -382,12 +390,16 @@ create_elf64(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, int fd, uint_t flags)
>   	shdr->sh_addralign = sizeof(char);
>   
>   	/* Add the provider definitions. */
> -	while ((pvp = dt_htab_next(dtp->dt_provs, &it)) != NULL)
> -		note_add_provider(usdt, pvp);
> +	while ((pvp = dt_htab_next(dtp->dt_provs, &it)) != NULL) {
> +		if (note_add_provider(usdt, pvp) == -1)
> +			goto fail;
> +	}
>   
>   	if (!(flags & DTRACE_D_STRIP)) {
> -		note_add_version(usdt);
> -		note_add_utsname(usdt);
> +		if (note_add_version(usdt) == -1)
> +			goto fail;
> +		if (note_add_utsname(usdt) == -1)
> +			goto fail;
>   	}
>   
>   	dt_free(dtp, usdt);
> @@ -492,7 +504,9 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
>   	if (!dtp->dt_lazyload)
>   		unlink(file);
>   
> -	create_elf64(dtp, pgp, fd, dflags | dtp->dt_dflags);
> +	ret = create_elf64(dtp, pgp, fd, dflags | dtp->dt_dflags);
> +	if (ret == -1)
> +		goto done;
>   
>   	if (status != 0 || lseek(fd, 0, SEEK_SET) != 0)
>   		return dt_link_error(dtp, NULL, -1,
> diff --git a/test/unittest/usdt/err.prov-too-long.r b/test/unittest/usdt/err.prov-too-long.r
> new file mode 100644
> index 00000000..1305f434
> --- /dev/null
> +++ b/test/unittest/usdt/err.prov-too-long.r
> @@ -0,0 +1,3 @@
> +-- @@stderr --
> +dtrace: failed to link script prov: USDT provider name may not exceed 53 characters: test_12345678901234567890123456789012345678901234_prov
> +failed to create DOF
> diff --git a/test/unittest/usdt/err.prov-too-long.sh b/test/unittest/usdt/err.prov-too-long.sh
> new file mode 100755
> index 00000000..599e461e
> --- /dev/null
> +++ b/test/unittest/usdt/err.prov-too-long.sh
> @@ -0,0 +1,41 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2026, 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.
> +#
> +
> +# Ensure that provider names longer than 53 chars are rejected at link time.
> +
> +if [ $# != 1 ]; then
> +	echo expected one argument: '<'dtrace-path'>'
> +	exit 2
> +fi
> +
> +
> +dtrace=$1
> +
> +DIRNAME="$tmpdir/prov-too-long.$$.$RANDOM"
> +mkdir -p $DIRNAME
> +cd $DIRNAME
> +
> +cat > prov.d <<EOF
> +/* Provider name is 53 chars long */
> +provider test_1234567890123456789012345678901234567890123_prov {
> +	probe go();
> +};
> +/* Provider name is 54 chars long */
> +provider test_12345678901234567890123456789012345678901234_prov {
> +	probe go();
> +};
> +EOF
> +
> +$dtrace $dt_flags -G -s prov.d
> +if [ $? -ne 0 ]; then
> +	echo "failed to create DOF" >& 2
> +	exit 1
> +fi
> +
> +echo "DOF creation should have failed" >& 2
> +exit 0