[PATCH] lnstat: Fix deref of null in print_json() function

[PATCH] lnstat: Fix deref of null in print_json() function

[Maks Mishin]

Now pointer `jw` is being checked for NULL before using
in function `jsonw_start_object`.
Added exit from function when `jw==NULL`.

Found by RASU JSC

Signed-off-by: Maks Mishin <maks.mishinFZ@gmail.com>
---
 misc/lnstat.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/misc/lnstat.c b/misc/lnstat.c
index c3f2999c..f802a0f3 100644
--- a/misc/lnstat.c
+++ b/misc/lnstat.c
@@ -112,6 +112,10 @@ static void print_json(FILE *of, const struct lnstat_file *lnstat_files,
 	json_writer_t *jw = jsonw_new(of);
 	int i;
 
+	if (jw == NULL) {
+		fprintf(stderr, "Failed to create JSON writer\n");
+		exit(1);
+	}
 	jsonw_start_object(jw);
 	for (i = 0; i < fp->num; i++) {
 		const struct lnstat_field *lf = fp->params[i].lf;
-- 
2.34.1

Re: [PATCH] lnstat: Fix deref of null in print_json() function

[Stephen Hemminger]

On Sat,  6 Jan 2024 22:04:23 +0300
Maks Mishin <maks.mishinfz@gmail.com> wrote:

> Now pointer `jw` is being checked for NULL before using
> in function `jsonw_start_object`.
> Added exit from function when `jw==NULL`.
> 
> Found by RASU JSC
> 
> Signed-off-by: Maks Mishin <maks.mishinFZ@gmail.com>

Probably not worth fixing.
If the malloc() of 20 bytes ever fails then something is really wrong.
The Linux kernel will kill the process first.

Re: [PATCH] lnstat: Fix deref of null in print_json() function

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to iproute2/iproute2.git (main)
by Stephen Hemminger <stephen@networkplumber.org>:

On Sat,  6 Jan 2024 22:04:23 +0300 you wrote:
> Now pointer `jw` is being checked for NULL before using
> in function `jsonw_start_object`.
> Added exit from function when `jw==NULL`.
> 
> Found by RASU JSC
> 
> Signed-off-by: Maks Mishin <maks.mishinFZ@gmail.com>
> 
> [...]

Here is the summary with links:
  - lnstat: Fix deref of null in print_json() function
    https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/commit/?id=a193733b7a7e

You are awesome, thank you!
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