[PATCH v2] kvm: fix memory leak on failure to read stats descriptors

[PATCH v2] kvm: fix memory leak on failure to read stats descriptors

[Paolo Bonzini]

Reported by Coverity as CID 1490142.  Since the size is constant and the
lifetime is the same as the StatsDescriptors struct, embed the struct
directly instead of using a separate allocation.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/kvm/kvm-all.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 7c8ce18bdd..5acab1767f 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3908,7 +3908,7 @@ exit:
 typedef struct StatsDescriptors {
     const char *ident; /* cache key, currently the StatsTarget */
     struct kvm_stats_desc *kvm_stats_desc;
-    struct kvm_stats_header *kvm_stats_header;
+    struct kvm_stats_header kvm_stats_header;
     QTAILQ_ENTRY(StatsDescriptors) next;
 } StatsDescriptors;
 
@@ -3939,7 +3939,7 @@ static StatsDescriptors *find_stats_descriptors(StatsTarget target, int stats_fd
     descriptors = g_new0(StatsDescriptors, 1);
 
     /* Read stats header */
-    kvm_stats_header = g_malloc(sizeof(*kvm_stats_header));
+    kvm_stats_header = &descriptors->kvm_stats_header;
     ret = read(stats_fd, kvm_stats_header, sizeof(*kvm_stats_header));
     if (ret != sizeof(*kvm_stats_header)) {
         error_setg(errp, "KVM stats: failed to read stats header: "
@@ -3964,7 +3964,6 @@ static StatsDescriptors *find_stats_descriptors(StatsTarget target, int stats_fd
         g_free(kvm_stats_desc);
         return NULL;
     }
-    descriptors->kvm_stats_header = kvm_stats_header;
     descriptors->kvm_stats_desc = kvm_stats_desc;
     descriptors->ident = ident;
     QTAILQ_INSERT_TAIL(&stats_descriptors, descriptors, next);
@@ -3989,7 +3988,7 @@ static void query_stats(StatsResultList **result, StatsTarget target,
         return;
     }
 
-    kvm_stats_header = descriptors->kvm_stats_header;
+    kvm_stats_header = &descriptors->kvm_stats_header;
     kvm_stats_desc = descriptors->kvm_stats_desc;
     size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
 
@@ -4054,7 +4053,7 @@ static void query_stats_schema(StatsSchemaList **result, StatsTarget target,
         return;
     }
 
-    kvm_stats_header = descriptors->kvm_stats_header;
+    kvm_stats_header = &descriptors->kvm_stats_header;
     kvm_stats_desc = descriptors->kvm_stats_desc;
     size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
 
-- 
2.37.2

Re: [PATCH v2] kvm: fix memory leak on failure to read stats descriptors

[Richard Henderson]

On 9/5/22 13:39, Paolo Bonzini wrote:
> Reported by Coverity as CID 1490142.  Since the size is constant and the
> lifetime is the same as the StatsDescriptors struct, embed the struct
> directly instead of using a separate allocation.
> 
> Suggested-by: Richard Henderson<richard.henderson@linaro.org>
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
>   accel/kvm/kvm-all.c | 9 ++++-----
>   1 file changed, 4 insertions(+), 5 deletions(-)

Thanks,

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

Re: [PATCH v2] kvm: fix memory leak on failure to read stats descriptors

[Philippe Mathieu-Daudé via]

On Mon, Sep 5, 2022 at 3:28 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> Reported by Coverity as CID 1490142.  Since the size is constant and the
> lifetime is the same as the StatsDescriptors struct, embed the struct
> directly instead of using a separate allocation.
>
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  accel/kvm/kvm-all.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>