[IRDA]: Fix rfcomm use-after-free
[pandora-kernel.git] / fs / compat.c
index 7b21b0a..15078ce 100644 (file)
@@ -1257,6 +1257,7 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
 {
        struct page *kmapped_page = NULL;
        char *kaddr = NULL;
+       unsigned long kpos = 0;
        int ret;
 
        while (argc-- > 0) {
@@ -1265,92 +1266,84 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
                unsigned long pos;
 
                if (get_user(str, argv+argc) ||
-                       !(len = strnlen_user(compat_ptr(str), bprm->p))) {
+                   !(len = strnlen_user(compat_ptr(str), MAX_ARG_STRLEN))) {
                        ret = -EFAULT;
                        goto out;
                }
 
-               if (bprm->p < len)  {
+               if (len > MAX_ARG_STRLEN) {
                        ret = -E2BIG;
                        goto out;
                }
 
-               bprm->p -= len;
-               /* XXX: add architecture specific overflow check here. */
+               /* We're going to work our way backwords. */
                pos = bprm->p;
+               str += len;
+               bprm->p -= len;
 
                while (len > 0) {
-                       int i, new, err;
                        int offset, bytes_to_copy;
-                       struct page *page;
 
                        offset = pos % PAGE_SIZE;
-                       i = pos/PAGE_SIZE;
-                       page = bprm->page[i];
-                       new = 0;
-                       if (!page) {
-                               page = alloc_page(GFP_HIGHUSER);
-                               bprm->page[i] = page;
-                               if (!page) {
-                                       ret = -ENOMEM;
+                       if (offset == 0)
+                               offset = PAGE_SIZE;
+
+                       bytes_to_copy = offset;
+                       if (bytes_to_copy > len)
+                               bytes_to_copy = len;
+
+                       offset -= bytes_to_copy;
+                       pos -= bytes_to_copy;
+                       str -= bytes_to_copy;
+                       len -= bytes_to_copy;
+
+                       if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
+                               struct page *page;
+
+#ifdef CONFIG_STACK_GROWSUP
+                               ret = expand_stack_downwards(bprm->vma, pos);
+                               if (ret < 0) {
+                                       /* We've exceed the stack rlimit. */
+                                       ret = -E2BIG;
+                                       goto out;
+                               }
+#endif
+                               ret = get_user_pages(current, bprm->mm, pos,
+                                                    1, 1, 1, &page, NULL);
+                               if (ret <= 0) {
+                                       /* We've exceed the stack rlimit. */
+                                       ret = -E2BIG;
                                        goto out;
                                }
-                               new = 1;
-                       }
 
-                       if (page != kmapped_page) {
-                               if (kmapped_page)
+                               if (kmapped_page) {
+                                       flush_kernel_dcache_page(kmapped_page);
                                        kunmap(kmapped_page);
+                                       put_page(kmapped_page);
+                               }
                                kmapped_page = page;
                                kaddr = kmap(kmapped_page);
+                               kpos = pos & PAGE_MASK;
+                               flush_cache_page(bprm->vma, kpos,
+                                                page_to_pfn(kmapped_page));
                        }
-                       if (new && offset)
-                               memset(kaddr, 0, offset);
-                       bytes_to_copy = PAGE_SIZE - offset;
-                       if (bytes_to_copy > len) {
-                               bytes_to_copy = len;
-                               if (new)
-                                       memset(kaddr+offset+len, 0,
-                                               PAGE_SIZE-offset-len);
-                       }
-                       err = copy_from_user(kaddr+offset, compat_ptr(str),
-                                               bytes_to_copy);
-                       if (err) {
+                       if (copy_from_user(kaddr+offset, compat_ptr(str),
+                                               bytes_to_copy)) {
                                ret = -EFAULT;
                                goto out;
                        }
-
-                       pos += bytes_to_copy;
-                       str += bytes_to_copy;
-                       len -= bytes_to_copy;
                }
        }
        ret = 0;
 out:
-       if (kmapped_page)
+       if (kmapped_page) {
+               flush_kernel_dcache_page(kmapped_page);
                kunmap(kmapped_page);
-       return ret;
-}
-
-#ifdef CONFIG_MMU
-
-#define free_arg_pages(bprm) do { } while (0)
-
-#else
-
-static inline void free_arg_pages(struct linux_binprm *bprm)
-{
-       int i;
-
-       for (i = 0; i < MAX_ARG_PAGES; i++) {
-               if (bprm->page[i])
-                       __free_page(bprm->page[i]);
-               bprm->page[i] = NULL;
+               put_page(kmapped_page);
        }
+       return ret;
 }
 
-#endif /* CONFIG_MMU */
-
 /*
  * compat_do_execve() is mostly a copy of do_execve(), with the exception
  * that it processes 32 bit argv and envp pointers.
@@ -1363,7 +1356,6 @@ int compat_do_execve(char * filename,
        struct linux_binprm *bprm;
        struct file *file;
        int retval;
-       int i;
 
        retval = -ENOMEM;
        bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
@@ -1377,24 +1369,19 @@ int compat_do_execve(char * filename,
 
        sched_exec();
 
-       bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
        bprm->file = file;
        bprm->filename = filename;
        bprm->interp = filename;
-       bprm->mm = mm_alloc();
-       retval = -ENOMEM;
-       if (!bprm->mm)
-               goto out_file;
 
-       retval = init_new_context(current, bprm->mm);
-       if (retval < 0)
-               goto out_mm;
+       retval = bprm_mm_init(bprm);
+       if (retval)
+               goto out_file;
 
-       bprm->argc = compat_count(argv, bprm->p / sizeof(compat_uptr_t));
+       bprm->argc = compat_count(argv, MAX_ARG_STRINGS);
        if ((retval = bprm->argc) < 0)
                goto out_mm;
 
-       bprm->envc = compat_count(envp, bprm->p / sizeof(compat_uptr_t));
+       bprm->envc = compat_count(envp, MAX_ARG_STRINGS);
        if ((retval = bprm->envc) < 0)
                goto out_mm;
 
@@ -1421,8 +1408,6 @@ int compat_do_execve(char * filename,
 
        retval = search_binary_handler(bprm, regs);
        if (retval >= 0) {
-               free_arg_pages(bprm);
-
                /* execve success */
                security_bprm_free(bprm);
                acct_update_integrals(current);
@@ -1431,19 +1416,12 @@ int compat_do_execve(char * filename,
        }
 
 out:
-       /* Something went wrong, return the inode and free the argument pages*/
-       for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
-               struct page * page = bprm->page[i];
-               if (page)
-                       __free_page(page);
-       }
-
        if (bprm->security)
                security_bprm_free(bprm);
 
 out_mm:
        if (bprm->mm)
-               mmdrop(bprm->mm);
+               mmput(bprm->mm);
 
 out_file:
        if (bprm->file) {
@@ -1544,9 +1522,10 @@ int compat_core_sys_select(int n, compat_ulong_t __user *inp,
        compat_ulong_t __user *outp, compat_ulong_t __user *exp, s64 *timeout)
 {
        fd_set_bits fds;
-       char *bits;
+       void *bits;
        int size, max_fds, ret = -EINVAL;
        struct fdtable *fdt;
+       long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
 
        if (n < 0)
                goto out_nofds;
@@ -1564,11 +1543,14 @@ int compat_core_sys_select(int n, compat_ulong_t __user *inp,
         * since we used fdset we need to allocate memory in units of
         * long-words.
         */
-       ret = -ENOMEM;
        size = FDS_BYTES(n);
-       bits = kmalloc(6 * size, GFP_KERNEL);
-       if (!bits)
-               goto out_nofds;
+       bits = stack_fds;
+       if (size > sizeof(stack_fds) / 6) {
+               bits = kmalloc(6 * size, GFP_KERNEL);
+               ret = -ENOMEM;
+               if (!bits)
+                       goto out_nofds;
+       }
        fds.in      = (unsigned long *)  bits;
        fds.out     = (unsigned long *) (bits +   size);
        fds.ex      = (unsigned long *) (bits + 2*size);
@@ -1600,7 +1582,8 @@ int compat_core_sys_select(int n, compat_ulong_t __user *inp,
            compat_set_fd_set(n, exp, fds.res_ex))
                ret = -EFAULT;
 out:
-       kfree(bits);
+       if (bits != stack_fds)
+               kfree(bits);
 out_nofds:
        return ret;
 }
@@ -2230,21 +2213,16 @@ asmlinkage long compat_sys_signalfd(int ufd,
 asmlinkage long compat_sys_timerfd(int ufd, int clockid, int flags,
                                   const struct compat_itimerspec __user *utmr)
 {
-       long res;
        struct itimerspec t;
        struct itimerspec __user *ut;
 
-       res = -EFAULT;
        if (get_compat_itimerspec(&t, utmr))
-               goto err_exit;
+               return -EFAULT;
        ut = compat_alloc_user_space(sizeof(*ut));
-       if (copy_to_user(ut, &t, sizeof(t)) )
-               goto err_exit;
+       if (copy_to_user(ut, &t, sizeof(t)))
+               return -EFAULT;
 
-       res = sys_timerfd(ufd, clockid, flags, ut);
-err_exit:
-       return res;
+       return sys_timerfd(ufd, clockid, flags, ut);
 }
 
 #endif /* CONFIG_TIMERFD */
-