Re: [PATCH for-4.17 v3 14/15] tools/ocaml/xenstored/syslog_stubs.c: avoid potential NULL dereference

[Julien Grall <julien@xxxxxxx>]

On 08/11/2022 15:34, Edwin Török wrote:
> If we are out of memory then strdup may return NULL, and passing NULL to
> syslog may cause a crash.
>
> Avoid this by using `caml_stat_strdup` which will raise an OCaml out of
> memory exception instead.
> This then needs to be paired with caml_stat_free.
>
> Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
> ---
> Reason for inclusion in 4.17:
> - fixes a bug in out of memory situations
>
> Changes since v2:
> - new in v3
> ---
>   tools/ocaml/xenstored/syslog_stubs.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/tools/ocaml/xenstored/syslog_stubs.c 
> b/tools/ocaml/xenstored/syslog_stubs.c
> index 4e5e49b557..4ad85c8eb5 100644
> --- a/tools/ocaml/xenstored/syslog_stubs.c
> +++ b/tools/ocaml/xenstored/syslog_stubs.c
> @@ -14,6 +14,7 @@
>   
>   #include <syslog.h>
>   #include <string.h>
> +#include <caml/fail.h>
>   #include <caml/mlvalues.h>
>   #include <caml/memory.h>
>   #include <caml/alloc.h>
> @@ -35,14 +36,16 @@ static int __syslog_facility_table[] = {
>   value stub_syslog(value facility, value level, value msg)
>   {
>       CAMLparam3(facility, level, msg);
> -    const char *c_msg = strdup(String_val(msg));
> +    char *c_msg = strdup(String_val(msg));
This change seems to be unrelated with the goal of the commit. IMHO, 
this should be done in a separate patch.
The minimum would be to mention in the commit message.

Cheers,

--
Julien Grall