[PATCH 3/4] net/dump: Avoid variable length array

Peter Maydell posted 4 patches 1 year, 3 months ago
Maintainers: Jason Wang <jasowang@redhat.com>, Jiri Pirko <jiri@resnulli.us>
[PATCH 3/4] net/dump: Avoid variable length array
Posted by Peter Maydell 1 year, 3 months ago
Use a g_autofree heap allocation instead of a variable length
array in dump_receive_iov().

The codebase has very few VLAs, and if we can get rid of them all we
can make the compiler error on new additions.  This is a defensive
measure against security bugs where an on-stack dynamic allocation
isn't correctly size-checked (e.g.  CVE-2021-3527).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 net/dump.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/dump.c b/net/dump.c
index 7d05f16ca7a..16073f24582 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -68,7 +68,7 @@ static ssize_t dump_receive_iov(DumpState *s, const struct iovec *iov, int cnt,
     int64_t ts;
     int caplen;
     size_t size = iov_size(iov, cnt) - offset;
-    struct iovec dumpiov[cnt + 1];
+    g_autofree struct iovec *dumpiov = g_new(struct iovec, cnt + 1);
 
     /* Early return in case of previous error. */
     if (s->fd < 0) {
-- 
2.34.1
Re: [PATCH 3/4] net/dump: Avoid variable length array
Posted by Francisco Iglesias 1 year, 3 months ago
On [2023 Aug 24] Thu 16:32:23, Peter Maydell wrote:
> Use a g_autofree heap allocation instead of a variable length
> array in dump_receive_iov().
> 
> The codebase has very few VLAs, and if we can get rid of them all we
> can make the compiler error on new additions.  This is a defensive
> measure against security bugs where an on-stack dynamic allocation
> isn't correctly size-checked (e.g.  CVE-2021-3527).
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>

> ---
>  net/dump.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/dump.c b/net/dump.c
> index 7d05f16ca7a..16073f24582 100644
> --- a/net/dump.c
> +++ b/net/dump.c
> @@ -68,7 +68,7 @@ static ssize_t dump_receive_iov(DumpState *s, const struct iovec *iov, int cnt,
>      int64_t ts;
>      int caplen;
>      size_t size = iov_size(iov, cnt) - offset;
> -    struct iovec dumpiov[cnt + 1];
> +    g_autofree struct iovec *dumpiov = g_new(struct iovec, cnt + 1);
>  
>      /* Early return in case of previous error. */
>      if (s->fd < 0) {
> -- 
> 2.34.1
> 
>