From 82fab442f5322b016f72891c0db2436c6a6c20b7 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 11 Dec 2012 09:38:33 +1030
Subject: [PATCH] modules: don't hand 0 to vmalloc.
In commit d0a21265dfb5fa8a David Rientjes unified various archs'
module_alloc implementation (including x86) and removed the graduitous
shortcut for size == 0.
Then, in commit de7d2b567d040e3b, Joe Perches added a warning for
zero-length vmallocs, which can happen without kallsyms on modules
with no init sections (eg. zlib_deflate).
Fix this once and for all; the module code has to handle zero length
anyway, so get it right at the caller and remove the now-gratuitous
checks within the arch-specific module_alloc implementations.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=42608
Reported-by: Conrad Kostecki <ConiKost@gmx.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
arch/cris/kernel/module.c | 2 --
arch/parisc/kernel/module.c | 2 --
arch/sparc/kernel/module.c | 4 ----
arch/tile/kernel/module.c | 2 --
arch/unicore32/kernel/module.c | 3 ---
kernel/module.c | 33 ++++++++++++++++++---------------
6 files changed, 18 insertions(+), 28 deletions(-)
diff --git a/arch/cris/kernel/module.c b/arch/cris/kernel/module.c
index 37400f5869e61..51123f985eb58 100644
--- a/arch/cris/kernel/module.c
+++ b/arch/cris/kernel/module.c
@@ -32,8 +32,6 @@
#ifdef CONFIG_ETRAX_KMALLOCED_MODULES
void *module_alloc(unsigned long size)
{
- if (size == 0)
- return NULL;
return kmalloc(size, GFP_KERNEL);
}
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 5e34ccf39a49e..2a625fb063e15 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -214,8 +214,6 @@ static inline int reassemble_22(int as22)
void *module_alloc(unsigned long size)
{
- if (size == 0)
- return NULL;
/* using RWX means less protection for modules, but it's
* easier than trying to map the text, data, init_text and
* init_data correctly */
diff --git a/arch/sparc/kernel/module.c b/arch/sparc/kernel/module.c
index f1ddc0d236794..4435488ebe258 100644
--- a/arch/sparc/kernel/module.c
+++ b/arch/sparc/kernel/module.c
@@ -43,10 +43,6 @@ void *module_alloc(unsigned long size)
{
void *ret;
- /* We handle the zero case fine, unlike vmalloc */
- if (size == 0)
- return NULL;
-
ret = module_map(size);
if (ret)
memset(ret, 0, size);
diff --git a/arch/tile/kernel/module.c b/arch/tile/kernel/module.c
index 243ffebe38d69..4918d91bc3a66 100644
--- a/arch/tile/kernel/module.c
+++ b/arch/tile/kernel/module.c
@@ -42,8 +42,6 @@ void *module_alloc(unsigned long size)
int i = 0;
int npages;
- if (size == 0)
- return NULL;
npages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
pages = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
if (pages == NULL)
diff --git a/arch/unicore32/kernel/module.c b/arch/unicore32/kernel/module.c
index 8fbe8577f5e69..16bd1495b9342 100644
--- a/arch/unicore32/kernel/module.c
+++ b/arch/unicore32/kernel/module.c
@@ -27,9 +27,6 @@ void *module_alloc(unsigned long size)
struct vm_struct *area;
size = PAGE_ALIGN(size);
- if (!size)
- return NULL;
-
area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
if (!area)
return NULL;
diff --git a/kernel/module.c b/kernel/module.c
index 79a526dd1b113..4542ff3f7ef96 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2377,7 +2377,7 @@ static void dynamic_debug_remove(struct _ddebug *debug)
void * __weak module_alloc(unsigned long size)
{
- return size == 0 ? NULL : vmalloc_exec(size);
+ return vmalloc_exec(size);
}
static void *module_alloc_update_bounds(unsigned long size)
@@ -2793,20 +2793,23 @@ static int move_module(struct module *mod, struct load_info *info)
memset(ptr, 0, mod->core_size);
mod->module_core = ptr;
- ptr = module_alloc_update_bounds(mod->init_size);
- /*
- * The pointer to this block is stored in the module structure
- * which is inside the block. This block doesn't need to be
- * scanned as it contains data and code that will be freed
- * after the module is initialized.
- */
- kmemleak_ignore(ptr);
- if (!ptr && mod->init_size) {
- module_free(mod, mod->module_core);
- return -ENOMEM;
- }
- memset(ptr, 0, mod->init_size);
- mod->module_init = ptr;
+ if (mod->init_size) {
+ ptr = module_alloc_update_bounds(mod->init_size);
+ /*
+ * The pointer to this block is stored in the module structure
+ * which is inside the block. This block doesn't need to be
+ * scanned as it contains data and code that will be freed
+ * after the module is initialized.
+ */
+ kmemleak_ignore(ptr);
+ if (!ptr) {
+ module_free(mod, mod->module_core);
+ return -ENOMEM;
+ }
+ memset(ptr, 0, mod->init_size);
+ mod->module_init = ptr;
+ } else
+ mod->module_init = NULL;
/* Transfer each section which specifies SHF_ALLOC */
pr_debug("final section addresses:\n");
--
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