[xen stable-4.16] tools/oxenstored/syslog: Avoid potential NULL dereference

[patchbot@xxxxxxx]

commit 4a8ff8bf1b32b4ff3ac8c472f0d861aa866a0fcf
Author:     Edwin Török <edvin.torok@xxxxxxxxxx>
AuthorDate: Tue Nov 8 14:24:19 2022 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Mon Dec 12 11:04:12 2022 +0000

    tools/oxenstored/syslog: Avoid potential NULL dereference
    
    strdup() may return NULL.  Check for this before passing to syslog().
    
    Drop const from c_msg.  It is bogus, as demonstrated by the need to cast to
    void * in order to free the memory.
    
    Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
    Acked-by: Christian Lindig <christian.lindig@xxxxxxxxxx>
    (cherry picked from commit acd3fb6d65905f8a185dcb9fe6a330a591b96203)
---
 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 875d48ad57..e16c3a9491 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));
        int c_facility = __syslog_facility_table[Int_val(facility)]
                       | __syslog_level_table[Int_val(level)];
 
+       if ( !c_msg )
+               caml_raise_out_of_memory();
        caml_enter_blocking_section();
        syslog(c_facility, "%s", c_msg);
        caml_leave_blocking_section();
 
-       free((void*)c_msg);
+       free(c_msg);
        CAMLreturn(Val_unit);
 }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16