* [PATCH][next] refperf: avoid null pointer dereference when buf fails to allocate
@ 2020-07-16 14:38 Colin King
2020-07-20 16:26 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Colin King @ 2020-07-16 14:38 UTC (permalink / raw)
To: Paul E . McKenney, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, Joel Fernandes, rcu
Cc: kernel-janitors, linux-kernel
From: Colin Ian King <colin.king@canonical.com>
Currently in the unlikely event that buf fails to be allocated it
is dereferenced a few times. Use the errexit flag to determine if
buf should be written to to avoid the null pointer dereferences.
Addresses-Coverity: ("Dereference after null check")
Fixes: f518f154ecef ("refperf: Dynamically allocate experiment-summary output buffer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
kernel/rcu/refscale.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index d9291f883b54..952595c678b3 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -546,9 +546,11 @@ static int main_func(void *arg)
// Print the average of all experiments
SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
- buf[0] = 0;
- strcat(buf, "\n");
- strcat(buf, "Runs\tTime(ns)\n");
+ if (!errexit) {
+ buf[0] = 0;
+ strcat(buf, "\n");
+ strcat(buf, "Runs\tTime(ns)\n");
+ }
for (exp = 0; exp < nruns; exp++) {
u64 avg;
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH][next] refperf: avoid null pointer dereference when buf fails to allocate
2020-07-16 14:38 [PATCH][next] refperf: avoid null pointer dereference when buf fails to allocate Colin King
@ 2020-07-20 16:26 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2020-07-20 16:26 UTC (permalink / raw)
To: Colin King
Cc: Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan,
Joel Fernandes, rcu, kernel-janitors, linux-kernel
On Thu, Jul 16, 2020 at 03:38:56PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently in the unlikely event that buf fails to be allocated it
> is dereferenced a few times. Use the errexit flag to determine if
> buf should be written to to avoid the null pointer dereferences.
>
> Addresses-Coverity: ("Dereference after null check")
> Fixes: f518f154ecef ("refperf: Dynamically allocate experiment-summary output buffer")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
Good catch, applied, thank you!
Thanx, Paul
> ---
> kernel/rcu/refscale.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
> index d9291f883b54..952595c678b3 100644
> --- a/kernel/rcu/refscale.c
> +++ b/kernel/rcu/refscale.c
> @@ -546,9 +546,11 @@ static int main_func(void *arg)
> // Print the average of all experiments
> SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
>
> - buf[0] = 0;
> - strcat(buf, "\n");
> - strcat(buf, "Runs\tTime(ns)\n");
> + if (!errexit) {
> + buf[0] = 0;
> + strcat(buf, "\n");
> + strcat(buf, "Runs\tTime(ns)\n");
> + }
>
> for (exp = 0; exp < nruns; exp++) {
> u64 avg;
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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