[nft] libnftables: Fix exit_cookie()

Message ID 20180613171824.23796-1-phil@nwl.cc
State Accepted
Delegated to: Pablo Neira
Headers show
Series
  • [nft] libnftables: Fix exit_cookie()
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Commit Message

Phil Sutter June 13, 2018, 5:18 p.m.
The output and error buffer feature depends on cookie->orig_fp to
indicate the current status of buffering: If it is set, a prior call to
init_cookie() is assumed. Though exit_cookie() missed to reset that
pointer to NULL. causing weird behaviour in applications if they do:

| nft = nft_ctx_new(0);
| nft_ctx_buffer_output(nft);
| nft_ctx_unbuffer_output(nft);
| nft_ctx_buffer_output(nft);

While being at it, apply the same fix to error path in init_cookie() as
well.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 src/libnftables.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Pablo Neira Ayuso June 18, 2018, 9:13 a.m. | #1
On Wed, Jun 13, 2018 at 07:18:24PM +0200, Phil Sutter wrote:
> The output and error buffer feature depends on cookie->orig_fp to
> indicate the current status of buffering: If it is set, a prior call to
> init_cookie() is assumed. Though exit_cookie() missed to reset that
> pointer to NULL. causing weird behaviour in applications if they do:
> 
> | nft = nft_ctx_new(0);
> | nft_ctx_buffer_output(nft);
> | nft_ctx_unbuffer_output(nft);
> | nft_ctx_buffer_output(nft);
> 
> While being at it, apply the same fix to error path in init_cookie() as
> well.

Applied, thanks.
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Patch

diff --git a/src/libnftables.c b/src/libnftables.c
index 5ee4b8965fc81..760deecf2b899 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -198,6 +198,7 @@  static int init_cookie(struct cookie *cookie)
 	cookie->fp = fopencookie(cookie, "w", cookie_fops);
 	if (!cookie->fp) {
 		cookie->fp = cookie->orig_fp;
+		cookie->orig_fp = NULL;
 		return 1;
 	}
 
@@ -211,6 +212,7 @@  static int exit_cookie(struct cookie *cookie)
 
 	fclose(cookie->fp);
 	cookie->fp = cookie->orig_fp;
+	cookie->orig_fp = NULL;
 	free(cookie->buf);
 	cookie->buf = NULL;
 	cookie->buflen = 0;