mtd: mtd_torturetest can cause stack overflows

mtd_torturetest uses the module parm "ebcnt" to control the size of a
stack based array of int's. When "ebcnt" is large, Ex: 1000, it
causes stack overflows on systems with small kernel stacks. The fix
is to move the array from the stack to kmalloc memory.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

diff --git a/drivers/mtd/tests/mtd_torturetest.c b/drivers/mtd/tests/mtd_torturetest.c
index c4cde1e9eddbb3026d4e8a9ab0a36f87dab566ae..3a9f6a6a79f99d4c5662ab3fc90051a23e2ffbed 100644 (file)
--- a/drivers/mtd/tests/mtd_torturetest.c
+++ b/drivers/mtd/tests/mtd_torturetest.c
@@ -208,7 +208,7 @@ static inline int write_pattern(int ebnum, void *buf)
 static int __init tort_init(void)
 {
        int err = 0, i, infinite = !cycles_count;
-       int bad_ebs[ebcnt];
+       int *bad_ebs;
 
        printk(KERN_INFO "\n");
        printk(KERN_INFO "=================================================\n");
@@ -250,28 +250,24 @@ static int __init tort_init(void)
 
        err = -ENOMEM;
        patt_5A5 = kmalloc(mtd->erasesize, GFP_KERNEL);
-       if (!patt_5A5) {
-               pr_err("error: cannot allocate memory\n");
+       if (!patt_5A5)
                goto out_mtd;
-       }
 
        patt_A5A = kmalloc(mtd->erasesize, GFP_KERNEL);
-       if (!patt_A5A) {
-               pr_err("error: cannot allocate memory\n");
+       if (!patt_A5A)
                goto out_patt_5A5;
-       }
 
        patt_FF = kmalloc(mtd->erasesize, GFP_KERNEL);
-       if (!patt_FF) {
-               pr_err("error: cannot allocate memory\n");
+       if (!patt_FF)
                goto out_patt_A5A;
-       }
 
        check_buf = kmalloc(mtd->erasesize, GFP_KERNEL);
-       if (!check_buf) {
-               pr_err("error: cannot allocate memory\n");
+       if (!check_buf)
                goto out_patt_FF;
-       }
+
+       bad_ebs = kcalloc(ebcnt, sizeof(*bad_ebs), GFP_KERNEL);
+       if (!bad_ebs)
+               goto out_check_buf;
 
        err = 0;
 
@@ -290,7 +286,6 @@ static int __init tort_init(void)
        /*
         * Check if there is a bad eraseblock among those we are going to test.
         */
-       memset(&bad_ebs[0], 0, sizeof(int) * ebcnt);
        if (mtd_can_have_bb(mtd)) {
                for (i = eb; i < eb + ebcnt; i++) {
                        err = mtd_block_isbad(mtd, (loff_t)i * mtd->erasesize);
@@ -394,6 +389,8 @@ out:
 
        pr_info("finished after %u erase cycles\n",
               erase_cycles);
+       kfree(bad_ebs);
+out_check_buf:
        kfree(check_buf);
 out_patt_FF:
        kfree(patt_FF);