linux-kernel - [PATCH v5 2/2] fs/binfmt_elf: Refactor load_elf

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Message-Id: <20220127124014.338760-3-akirakawata1@gmail.com>
Date:   Thu, 27 Jan 2022 21:40:17 +0900
From:   Akira Kawata <akirakawata1@...il.com>
To:     akpm@...ux-foundation.org, adobriyan@...il.com,
        viro@...iv.linux.org.uk, keescook@...omium.org,
        linux-fsdevel@...r.kernel.org, lukas.bulwahn@...il.com
Cc:     akirakawata1@...il.com, Eric Biederman <ebiederm@...ssion.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v5 2/2] fs/binfmt_elf: Refactor load_elf_binary function

I delete load_addr because it is not used anymore. And I rename
load_addr_set to first_pt_load because it is used only to capture the
first iteration of the loop.

Signed-off-by: Akira Kawata <akirakawata1@...il.com>
Acked-by: Kees Cook <keescook@...omium.org>
---
 fs/binfmt_elf.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index d120ab03795f..3218ebfde409 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -822,8 +822,8 @@ static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr,
 static int load_elf_binary(struct linux_binprm *bprm)
 {
 	struct file *interpreter = NULL; /* to shut gcc up */
-	unsigned long load_addr, load_bias = 0, phdr_addr = 0;
-	int load_addr_set = 0;
+	unsigned long load_bias = 0, phdr_addr = 0;
+	int first_pt_load = 1;
 	unsigned long error;
 	struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL;
 	struct elf_phdr *elf_property_phdata = NULL;
@@ -1073,12 +1073,12 @@ static int load_elf_binary(struct linux_binprm *bprm)
 
 		vaddr = elf_ppnt->p_vaddr;
 		/*
-		 * The first time through the loop, load_addr_set is false:
+		 * The first time through the loop, first_pt_load is true:
 		 * layout will be calculated. Once set, use MAP_FIXED since
 		 * we know we've already safely mapped the entire region with
 		 * MAP_FIXED_NOREPLACE in the once-per-binary logic following.
 		 */
-		if (load_addr_set) {
+		if (!first_pt_load) {
 			elf_flags |= MAP_FIXED;
 		} else if (elf_ex->e_type == ET_EXEC) {
 			/*
@@ -1138,10 +1138,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
 
 		/*
 		 * Calculate the entire size of the ELF mapping (total_size).
-		 * (Note that load_addr_set is set to true later once the
+		 * (Note that first_pt_load is set to false later once the
 		 * initial mapping is performed.)
 		 */
-		if (!load_addr_set) {
+		if (first_pt_load) {
 			total_size = total_mapping_size(elf_phdata,
 							elf_ex->e_phnum);
 			if (!total_size) {
@@ -1158,13 +1158,11 @@ static int load_elf_binary(struct linux_binprm *bprm)
 			goto out_free_dentry;
 		}
 
-		if (!load_addr_set) {
-			load_addr_set = 1;
-			load_addr = (elf_ppnt->p_vaddr - elf_ppnt->p_offset);
+		if (first_pt_load) {
+			first_pt_load = 0;
 			if (elf_ex->e_type == ET_DYN) {
 				load_bias += error -
 				             ELF_PAGESTART(load_bias + vaddr);
-				load_addr += load_bias;
 				reloc_func_desc = load_bias;
 			}
 		}
-- 
2.25.1