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@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220127124014.338760-3-akirakawata1@gmail.com

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 600cec2173c8930913cae7bd6b032a4b0c01303f..4c5a2175f6053e4a92aa2fabc962d4def1faac3a 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -824,8 +824,8 @@ 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;
@@ -1075,12 +1075,12 @@ out_free_interp:
 
                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) {
                        /*
@@ -1171,13 +1171,11 @@ out_free_interp:
                        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;
                        }
                }