1 files changed, 34 insertions, 16 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 3155e915307a..f1691cd0c9d2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -982,33 +982,51 @@ void compute_creds(struct linux_binprm *bprm)
         task_unlock(current);
         security_bprm_post_apply_creds(bprm);
 }
-
 EXPORT_SYMBOL(compute_creds);
 
+/*
+ * Arguments are '\0' separated strings found at the location bprm->p
+ * points to; chop off the first by relocating brpm->p to right after
+ * the first '\0' encountered.
+ */
 void remove_arg_zero(struct linux_binprm *bprm)
 {
         if (bprm->argc) {
-                unsigned long offset;
-                char * kaddr;
-                struct page *page;
+                char ch;
 
-                offset = bprm->p % PAGE_SIZE;
-                goto inside;
+                do {
+                        unsigned long offset;
+                        unsigned long index;
+                        char *kaddr;
+                        struct page *page;
 
-                while (bprm->p++, *(kaddr+offset++)) {
-                        if (offset != PAGE_SIZE)
-                                continue;
-                        offset = 0;
-                        kunmap_atomic(kaddr, KM_USER0);
-inside:
-                        page = bprm->page[bprm->p/PAGE_SIZE];
+                        offset = bprm->p & ~PAGE_MASK;
+                        index = bprm->p >> PAGE_SHIFT;
+
+                        page = bprm->page[index];
                         kaddr = kmap_atomic(page, KM_USER0);
-                }
-                kunmap_atomic(kaddr, KM_USER0);
+
+                        /* run through page until we reach end or find NUL */
+                        do {
+                                ch = *(kaddr + offset);
+
+                                /* discard that character... */
+                                bprm->p++;
+                                offset++;
+                        } while (offset < PAGE_SIZE && ch != '\0');
+
+                        kunmap_atomic(kaddr, KM_USER0);
+
+                        /* free the old page */
+                        if (offset == PAGE_SIZE) {
+                                __free_page(page);
+                                bprm->page[index] = NULL;
+                        }
+                } while (ch != '\0');
+
                 bprm->argc--;
         }
 }
-
 EXPORT_SYMBOL(remove_arg_zero);
 
 /*