Libguestfs - Apr 2018 - [PATCH] common/mlpcre: fix access to freed memory

free_last_match() frees the memory of the match passed as argument, so
accessing it is not possible after free_last_match().  Since all we
need is the return code, save it locally for later usage.
---
 common/mlpcre/pcre-c.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/common/mlpcre/pcre-c.c b/common/mlpcre/pcre-c.c
index da982025f..0762a8341 100644
--- a/common/mlpcre/pcre-c.c
+++ b/common/mlpcre/pcre-c.c
@@ -207,8 +207,9 @@ guestfs_int_pcre_matches (value rev, value strv)
 
   m->r = pcre_exec (re, NULL, m->subject, len, 0, 0, m->vec, veclen);
   if (m->r < 0 && m->r != PCRE_ERROR_NOMATCH) {
+    int ret = m->r;
     free_last_match (m);
-    raise_pcre_error ("pcre_exec", m->r);
+    raise_pcre_error ("pcre_exec", ret);
   }
 
   /* This error would indicate that pcre_exec ran out of space in the
-- 
2.14.3

On Fri, Apr 27, 2018 at 04:30:11PM +0200, Pino Toscano
wrote:
> free_last_match() frees the memory of the match passed as argument, so
> accessing it is not possible after free_last_match().  Since all we
> need is the return code, save it locally for later usage.
> ---
>  common/mlpcre/pcre-c.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/common/mlpcre/pcre-c.c b/common/mlpcre/pcre-c.c
> index da982025f..0762a8341 100644
> --- a/common/mlpcre/pcre-c.c
> +++ b/common/mlpcre/pcre-c.c
> @@ -207,8 +207,9 @@ guestfs_int_pcre_matches (value rev, value strv)
>  
>    m->r = pcre_exec (re, NULL, m->subject, len, 0, 0, m->vec,
veclen);
>    if (m->r < 0 && m->r != PCRE_ERROR_NOMATCH) {
> +    int ret = m->r;
>      free_last_match (m);
> -    raise_pcre_error ("pcre_exec", m->r);
> +    raise_pcre_error ("pcre_exec", ret);
>    }
Oops.

ACK, thanks.

Rich.

-- 
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