linux-kernel - [PATCH v2 1/6] module: fix kmemleak annotations for non init ELF sections

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Date:   Tue,  4 Apr 2023 19:26:57 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     david@...hat.com, patches@...ts.linux.dev,
        linux-modules@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, pmladek@...e.com,
        petr.pavlu@...e.com, prarit@...hat.com,
        torvalds@...ux-foundation.org, gregkh@...uxfoundation.org,
        rafael@...nel.org
Cc:     christophe.leroy@...roup.eu, tglx@...utronix.de,
        peterz@...radead.org, song@...nel.org, rppt@...nel.org,
        dave@...olabs.net, willy@...radead.org, vbabka@...e.cz,
        mhocko@...e.com, dave.hansen@...ux.intel.com,
        colin.i.king@...il.com, jim.cromie@...il.com,
        catalin.marinas@....com, jbaron@...mai.com,
        rick.p.edgecombe@...el.com, mcgrof@...nel.org
Subject: [PATCH v2 1/6] module: fix kmemleak annotations for non init ELF sections

Commit ac3b43283923 ("module: replace module_layout with module_memory")
reworked the way to handle memory allocations to make it clearer. But it
lost in translation how we handled kmemleak_ignore() or kmemleak_not_leak()
for different ELF sections.

Fix this and clarify the comments a bit more.

Fixes: ac3b43283923 ("module: replace module_layout with module_memory")
Reported-by: Jim Cromie <jim.cromie@...il.com>
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 kernel/module/main.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 5cc21083af04..d8bb23fa6989 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2233,11 +2233,23 @@ static int move_module(struct module *mod, struct load_info *info)
 		ptr = module_memory_alloc(mod->mem[type].size, type);
 
 		/*
-		 * The pointer to this block is stored in the module structure
-		 * which is inside the block. Just mark it as not being a
-		 * leak.
+		 * The pointer to these blocks of memory are stored on the module
+		 * structure and we keep that around so long as the module is
+		 * around. We only free that memory when we unload the module.
+		 * Just mark them as not being a leak then. The .init* ELF
+		 * sections *do* get freed after boot so we treat them slightly
+		 * differently and only grey them out -- they work as typical
+		 * memory allocations which *do* eventually get freed.
 		 */
-		kmemleak_ignore(ptr);
+		switch (type) {
+		case MOD_INIT_TEXT: /* fallthrough */
+		case MOD_INIT_DATA: /* fallthrough */
+		case MOD_INIT_RODATA: /* fallthrough */
+			kmemleak_ignore(ptr);
+			break;
+		default:
+			kmemleak_not_leak(ptr);
+		}
 		if (!ptr) {
 			t = type;
 			goto out_enomem;
-- 
2.39.2