[1/1] libsepol/cil: silence static analyser's use-after-free warning
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Message ID 20190206210752.11828-1-nicolas.iooss@m4x.org
State Accepted
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Series
  • [1/1] libsepol/cil: silence static analyser's use-after-free warning
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Commit Message

Nicolas Iooss Feb. 6, 2019, 9:07 p.m. UTC
clang's static analyze reports a use-after-free in
__cil_expr_to_string(), when __cil_expr_to_string_helper() does not
modify its third parameter (variable s1 here) in this loop:

    for (curr = curr->next; curr; curr = curr->next) {
        __cil_expr_to_string_helper(curr, flavor, &s1);
        cil_asprintf(&c2, "%s %s", c1, s1);
        free(c1);
        free(s1);
        c1 = c2;
    }

Silence this warning by making sure s1 is always NULL at the beginning
of every iteration of the loop.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
---
 libsepol/cil/src/cil_binary.c | 1 +
 1 file changed, 1 insertion(+)

Comments

jwcart2 Feb. 11, 2019, 7:06 p.m. UTC | #1
On 2/6/19 4:07 PM, Nicolas Iooss wrote:
> clang's static analyze reports a use-after-free in
> __cil_expr_to_string(), when __cil_expr_to_string_helper() does not
> modify its third parameter (variable s1 here) in this loop:
> 
>      for (curr = curr->next; curr; curr = curr->next) {
>          __cil_expr_to_string_helper(curr, flavor, &s1);
>          cil_asprintf(&c2, "%s %s", c1, s1);
>          free(c1);
>          free(s1);
>          c1 = c2;
>      }
> 
> Silence this warning by making sure s1 is always NULL at the beginning
> of every iteration of the loop.
> 
> Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>

Acked-by: James Carter <jwcart2@tycho.nsa.gov>

> ---
>   libsepol/cil/src/cil_binary.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/libsepol/cil/src/cil_binary.c b/libsepol/cil/src/cil_binary.c
> index a10c3763bea4..e2eb3ebe8ff3 100644
> --- a/libsepol/cil/src/cil_binary.c
> +++ b/libsepol/cil/src/cil_binary.c
> @@ -2075,6 +2075,7 @@ static void __cil_expr_to_string(struct cil_list *expr, enum cil_flavor flavor,
>   		char *c2 = NULL;
>   		__cil_expr_to_string_helper(curr, flavor, &c1);
>   		for (curr = curr->next; curr; curr = curr->next) {
> +			s1 = NULL;
>   			__cil_expr_to_string_helper(curr, flavor, &s1);
>   			cil_asprintf(&c2, "%s %s", c1, s1);
>   			free(c1);
>
Nicolas Iooss Feb. 12, 2019, 9:01 p.m. UTC | #2
On Mon, Feb 11, 2019 at 8:06 PM jwcart2 <jwcart2@tycho.nsa.gov> wrote:
>
> On 2/6/19 4:07 PM, Nicolas Iooss wrote:
> > clang's static analyze reports a use-after-free in
> > __cil_expr_to_string(), when __cil_expr_to_string_helper() does not
> > modify its third parameter (variable s1 here) in this loop:
> >
> >      for (curr = curr->next; curr; curr = curr->next) {
> >          __cil_expr_to_string_helper(curr, flavor, &s1);
> >          cil_asprintf(&c2, "%s %s", c1, s1);
> >          free(c1);
> >          free(s1);
> >          c1 = c2;
> >      }
> >
> > Silence this warning by making sure s1 is always NULL at the beginning
> > of every iteration of the loop.
> >
> > Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
>
> Acked-by: James Carter <jwcart2@tycho.nsa.gov>

Merged.

Nicolas

> > ---
> >   libsepol/cil/src/cil_binary.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/libsepol/cil/src/cil_binary.c b/libsepol/cil/src/cil_binary.c
> > index a10c3763bea4..e2eb3ebe8ff3 100644
> > --- a/libsepol/cil/src/cil_binary.c
> > +++ b/libsepol/cil/src/cil_binary.c
> > @@ -2075,6 +2075,7 @@ static void __cil_expr_to_string(struct cil_list *expr, enum cil_flavor flavor,
> >               char *c2 = NULL;
> >               __cil_expr_to_string_helper(curr, flavor, &c1);
> >               for (curr = curr->next; curr; curr = curr->next) {
> > +                     s1 = NULL;
> >                       __cil_expr_to_string_helper(curr, flavor, &s1);
> >                       cil_asprintf(&c2, "%s %s", c1, s1);
> >                       free(c1);
> >
>
>
> --
> James Carter <jwcart2@tycho.nsa.gov>
> National Security Agency

Patch
diff mbox series

diff --git a/libsepol/cil/src/cil_binary.c b/libsepol/cil/src/cil_binary.c
index a10c3763bea4..e2eb3ebe8ff3 100644
--- a/libsepol/cil/src/cil_binary.c
+++ b/libsepol/cil/src/cil_binary.c
@@ -2075,6 +2075,7 @@  static void __cil_expr_to_string(struct cil_list *expr, enum cil_flavor flavor,
 		char *c2 = NULL;
 		__cil_expr_to_string_helper(curr, flavor, &c1);
 		for (curr = curr->next; curr; curr = curr->next) {
+			s1 = NULL;
 			__cil_expr_to_string_helper(curr, flavor, &s1);
 			cil_asprintf(&c2, "%s %s", c1, s1);
 			free(c1);