linux-kernel - Re: [PATCH v10] module: replace module_layout with module

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Message-ID: <8972F26D-34FE-4463-83AD-BBCC6F92C952@fb.com>
Date:   Tue, 7 Feb 2023 22:19:30 +0000
From:   Song Liu <songliubraving@...a.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
CC:     "linux-modules@...r.kernel.org" <linux-modules@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Kernel Team <kernel-team@...a.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Song Liu <song@...nel.org>
Subject: Re: [PATCH v10] module: replace module_layout with module_memory

Hi Luis

> On Feb 6, 2023, at 4:28 PM, Song Liu <song@...nel.org> wrote:
> 
> +static void free_mod_mem(struct module *mod)
> +{
> + /* free the memory in the right order to avoid use-after-free */
> + static enum mod_mem_type mod_mem_free_order[MOD_MEM_NUM_TYPES] = {
> + /* first free init sections */
> + MOD_INIT_TEXT,
> + MOD_INIT_DATA,
> + MOD_INIT_RODATA,
> +
> + /* then core sections, except rw data */
> + MOD_TEXT,
> + MOD_RODATA,
> + MOD_RO_AFTER_INIT,
> +
> + /* last, rw data */
> + MOD_DATA,
> + };
> + int i;
> +
> + BUILD_BUG_ON(ARRAY_SIZE(mod_mem_free_order) != MOD_MEM_NUM_TYPES);
> +
> + for (i = 0; i < MOD_MEM_NUM_TYPES; i++) {
> + enum mod_mem_type type = mod_mem_free_order[i];
> + struct module_memory *mod_mem = &mod->mem[type];
> +
> + /* Free lock-classes; relies on the preceding sync_rcu(). */
> + lockdep_free_key_range(mod_mem->base, mod_mem->size);
> + if (mod_mem->size)
> + module_memory_free(mod_mem->base, type);
> + }
> +}

If there are no other comments, would you mind make the following 
change when applying the patch?

Thanks,
Song


diff --git i/kernel/module/main.c w/kernel/module/main.c
index b9617d7e8db2..c598f11e7016 100644
--- i/kernel/module/main.c
+++ w/kernel/module/main.c
@@ -1211,7 +1211,7 @@ static void free_mod_mem(struct module *mod)
		MOD_RODATA,
		MOD_RO_AFTER_INIT,

-		/* last, rw data */
+		/* rw data need to be freed last, as it hosts mod */
		MOD_DATA,
	};
	int i;