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>

5 files changed, 0 insertions, 13 deletions

diff --git a/arch/cris/kernel/module.c b/arch/cris/kernel/module.c
index 37400f5..51123f9 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 5e34ccf..2a625fb 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 f1ddc0d..4435488 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 243ffeb..4918d91 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 8fbe857..16bd149 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;