linux-kernel - [PATCH v2] module: Refine kmemleak scanned areas

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Message-ID: <20240910073123.2362028-1-vdonnefort@google.com>
Date: Tue, 10 Sep 2024 08:31:23 +0100
From: Vincent Donnefort <vdonnefort@...gle.com>
To: mcgrof@...nel.org
Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kernel-team@...roid.com, Vincent Donnefort <vdonnefort@...gle.com>, Song Liu <song@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH v2] module: Refine kmemleak scanned areas

commit ac3b43283923 ("module: replace module_layout with module_memory")
introduced a set of memory regions for the module layout sharing the
same attributes. However, it didn't update the kmemleak scanned areas
which intended to limit kmemleak scan to sections containing writable
data. This means sections such as .text and .rodata are scanned by
kmemleak.

Refine the scanned areas for modules by limiting it to MOD_TEXT and
MOD_INIT_TEXT mod_mem regions.

CC: Song Liu <song@...nel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Vincent Donnefort <vdonnefort@...gle.com>

---

v1 -> v2:
  - Collect Reviewed-by tag

diff --git a/kernel/module/debug_kmemleak.c b/kernel/module/debug_kmemleak.c
index 12a569d361e8..b4cc03842d70 100644
--- a/kernel/module/debug_kmemleak.c
+++ b/kernel/module/debug_kmemleak.c
@@ -12,19 +12,9 @@
 void kmemleak_load_module(const struct module *mod,
 			  const struct load_info *info)
 {
-	unsigned int i;
-
-	/* only scan the sections containing data */
-	kmemleak_scan_area(mod, sizeof(struct module), GFP_KERNEL);
-
-	for (i = 1; i < info->hdr->e_shnum; i++) {
-		/* Scan all writable sections that's not executable */
-		if (!(info->sechdrs[i].sh_flags & SHF_ALLOC) ||
-		    !(info->sechdrs[i].sh_flags & SHF_WRITE) ||
-		    (info->sechdrs[i].sh_flags & SHF_EXECINSTR))
-			continue;
-
-		kmemleak_scan_area((void *)info->sechdrs[i].sh_addr,
-				   info->sechdrs[i].sh_size, GFP_KERNEL);
+	/* only scan writable, non-executable sections */
+	for_each_mod_mem_type(type) {
+		if (type != MOD_DATA && type != MOD_INIT_DATA)
+			kmemleak_no_scan(mod->mem[type].base);
 	}
 }

base-commit: 431c1646e1f86b949fa3685efc50b660a364c2b6
-- 
2.46.0.598.g6f2099f65c-goog