Re: [PATCH 1/2] powerpc: Free fdt on error in elf64_load()

[Lakshmi Ramasubramanian]

On 4/21/21 12:18 AM, Michael Ellerman wrote:

Lakshmi Ramasubramanian <nra...@linux.microsoft.com> writes:

There are a few "goto out;" statements before the local variable "fdt"
is initialized through the call to of_kexec_alloc_and_setup_fdt() in
elf64_load().  This will result in an uninitialized "fdt" being passed
to kvfree() in this function if there is an error before the call to
of_kexec_alloc_and_setup_fdt().

If there is any error after fdt is allocated, but before it is
saved in the arch specific kimage struct, free the fdt.

Signed-off-by: Lakshmi Ramasubramanian <nra...@linux.microsoft.com>
Reported-by: kernel test robot <l...@intel.com>
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Suggested-by: Michael Ellerman <m...@ellerman.id.au>

I basically sent you the diff, so this should probably be:

   Reported-by: kernel test robot <l...@intel.com>
   Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
   Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
   Signed-off-by: Lakshmi Ramasubramanian <nra...@linux.microsoft.com>

Otherwise looks good to me, thanks for turning it into a proper patch
and submitting it.

I will submit the patch again with the above change.
Thanks for reviewing the patch.

Could you please review [PATCH 2/2] as well?

thanks,
 -lakshmi

cheers

diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 5a569bb51349..02662e72c53d 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -114,7 +114,7 @@ static void *elf64_load(struct kimage *image, char 
*kernel_buf,
        ret = setup_new_fdt_ppc64(image, fdt, initrd_load_addr,
                                  initrd_len, cmdline);
        if (ret)
-               goto out;
+               goto out_free_fdt;

fdt_pack(fdt); @@ -125,7 +125,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,

        kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
        ret = kexec_add_buffer(&kbuf);
        if (ret)
-               goto out;
+               goto out_free_fdt;

/* FDT will be freed in arch_kimage_file_post_load_cleanup */

        image->arch.fdt = fdt;
@@ -140,18 +140,14 @@ static void *elf64_load(struct kimage *image, char 
*kernel_buf,
        if (ret)
                pr_err("Error setting up the purgatory.\n");

+ goto out;

+
+out_free_fdt:
+       kvfree(fdt);
  out:
        kfree(modified_cmdline);
        kexec_free_elf_info(&elf_info);

- /*

-        * Once FDT buffer has been successfully passed to kexec_add_buffer(),
-        * the FDT buffer address is saved in image->arch.fdt. In that case,
-        * the memory cannot be freed here in case of any other error.
-        */
-       if (ret && !image->arch.fdt)
-               kvfree(fdt);
-
        return ret ? ERR_PTR(ret) : NULL;
  }

--

2.31.0