fs/binfmt_elf.c: allocate less for static executable

PT_INTERP ELF header can be spared if executable is static.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200219185012.GB4871@avx2
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 3cb888cb2b2b515bceefe4d5a6b6e37f3af1fcb1..a3a9429ef1d2a25fb114da3917ebdb6ba94a3a90 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -699,17 +699,11 @@ static int load_elf_binary(struct linux_binprm *bprm)
        unsigned long reloc_func_desc __maybe_unused = 0;
        int executable_stack = EXSTACK_DEFAULT;
        struct elfhdr *elf_ex = (struct elfhdr *)bprm->buf;
-       struct elfhdr *interp_elf_ex;
+       struct elfhdr *interp_elf_ex = NULL;
        struct arch_elf_state arch_state = INIT_ARCH_ELF_STATE;
        struct mm_struct *mm;
        struct pt_regs *regs;
 
-       interp_elf_ex = kmalloc(sizeof(*interp_elf_ex), GFP_KERNEL);
-       if (!interp_elf_ex) {
-               retval = -ENOMEM;
-               goto out_ret;
-       }
-
        retval = -ENOEXEC;
        /* First of all, some simple consistency checks */
        if (memcmp(elf_ex->e_ident, ELFMAG, SELFMAG) != 0)
@@ -769,6 +763,12 @@ static int load_elf_binary(struct linux_binprm *bprm)
                 */
                would_dump(bprm, interpreter);
 
+               interp_elf_ex = kmalloc(sizeof(*interp_elf_ex), GFP_KERNEL);
+               if (!interp_elf_ex) {
+                       retval = -ENOMEM;
+                       goto out_free_ph;
+               }
+
                /* Get the exec headers */
                retval = elf_read(interpreter, interp_elf_ex,
                                  sizeof(*interp_elf_ex), 0);
@@ -1074,6 +1074,8 @@ out_free_interp:
 
                allow_write_access(interpreter);
                fput(interpreter);
+
+               kfree(interp_elf_ex);
        } else {
                elf_entry = e_entry;
                if (BAD_ADDR(elf_entry)) {
@@ -1152,12 +1154,11 @@ out_free_interp:
        start_thread(regs, elf_entry, bprm->p);
        retval = 0;
 out:
-       kfree(interp_elf_ex);
-out_ret:
        return retval;
 
        /* error cleanup */
 out_free_dentry:
+       kfree(interp_elf_ex);
        kfree(interp_elf_phdata);
        allow_write_access(interpreter);
        if (interpreter)