[RFC] dpaa2: replace system("echo ...") with file i/o

[Stephen Hemminger]

Using system() is a bad idea in driver code because it introduces
a number of potential security issues. The codeql analysis tool
flags this a potential security issue.

Instead just use normal stdio to do the same thing.

Compile test only, do not have this hardware and therefore can
not test this.

Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
---
 drivers/bus/fslmc/portal/dpaa2_hw_dpio.c | 33 +++++++++++++++---------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/bus/fslmc/portal/dpaa2_hw_dpio.c 
b/drivers/bus/fslmc/portal/dpaa2_hw_dpio.c
index 22c51c1a82cc..894871aec19e 100644
--- a/drivers/bus/fslmc/portal/dpaa2_hw_dpio.c
+++ b/drivers/bus/fslmc/portal/dpaa2_hw_dpio.c
@@ -125,12 +125,12 @@ static void
 dpaa2_affine_dpio_intr_to_respective_core(int32_t dpio_id, int cpu_id)
 {
 #define STRING_LEN     28
-#define COMMAND_LEN    50
+#define AFFINITY_LEN   128
        uint32_t cpu_mask = 1;
-       int ret;
        size_t len = 0;
        char *temp = NULL, *token = NULL;
-       char string[STRING_LEN], command[COMMAND_LEN];
+       char string[STRING_LEN];
+       char smp_affinity[AFFINITY_LEN];
        FILE *file;
 
        snprintf(string, STRING_LEN, "dpio.%d", dpio_id);
@@ -153,18 +153,27 @@ dpaa2_affine_dpio_intr_to_respective_core(int32_t 
dpio_id, int cpu_id)
                fclose(file);
                return;
        }
+       free(temp);
+       fclose(file);
 
+       snprintf(smp_affinity, AFFINITY_LEN,
+                "/proc/irq/%s/smp_affinity", token);
        cpu_mask = cpu_mask << cpu_id;
-       snprintf(command, COMMAND_LEN, "echo %X > /proc/irq/%s/smp_affinity",
-                cpu_mask, token);
-       ret = system(command);
-       if (ret < 0)
-               DPAA2_BUS_DEBUG(
-                       "Failed to affine interrupts on respective core");
-       else
-               DPAA2_BUS_DEBUG(" %s command is executed", command);
 
-       free(temp);
+       file = fopen(smp_affinity, "w");
+       if (file == NULL) {
+               DPAA2_BUS_WARN("Failed to open %s", smp_affinity);
+               return;
+       }
+       fprintf(file, "%X\n", cpu_mask);
+       fflush(file);
+
+       if (ferror(file)) {
+               fclose(file);
+               DPAA2_BUS_WARN("Failed to write to %s", smp_affinity);
+               return;
+       }
+
        fclose(file);
 }
 
-- 
2.35.1