From 82fab442f5322b016f72891c0db2436c6a6c20b7 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Tue, 11 Dec 2012 09:38:33 +1030 Subject: 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 Cc: David Rientjes Cc: Joe Perches Signed-off-by: Rusty Russell --- 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 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; diff --git a/kernel/module.c b/kernel/module.c index 79a526d..4542ff3 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"); -- cgit v1.1