Re: [PATCH] commands/file: Fix null dereference in the knetbsd tests

[ross . philipson]

On 1/5/25 12:24 AM, Glenn Washburn wrote:
> From: Lukas Fink <lukas.fink1@gmail.com>
>
> The pointer returned by grub_elf_file() is not checked to verify it is not
> null before use. A null pointer may be returned when the given file does
> not have a valid ELF header.

Indeed or for a number of other reasons. Also other places in the switch 
check if elf == NULL.

Reviewed-by: Ross Philipson <ross.philipson@oracle.com>

> Fixes: 
> https://urldefense.com/v3/__https://savannah.gnu.org/bugs/?61960__;!!ACWV5N9M2RV99hQ!L8SmY4a1GhbF_jVSw1PgVVFTw85_c8-DzevGhhPXEAKZLBZhWQ7SbtR_O2rbR-lveEUY8m7Cws9K8J_FRnsDwnLMzXoo$
> Signed-off-by: Lukas Fink <lukas.fink1@gmail.com>
> Signed-off-by: Glenn Washburn <development@efficientek.com>
> ---
>   grub-core/commands/file.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/grub-core/commands/file.c b/grub-core/commands/file.c
> index 7c13e976b505..19602d75786b 100644
> --- a/grub-core/commands/file.c
> +++ b/grub-core/commands/file.c
> @@ -306,6 +306,8 @@ grub_cmd_file (grub_extcmd_context_t ctxt, int argc, char 
> **args)
>   
>   	elf = grub_elf_file (file, file->name);
>   
> +	if (elf == NULL)
> +         break;
>         if (elf->ehdr.ehdr32.e_type != grub_cpu_to_le16_compile_time (ET_EXEC)
>             || elf->ehdr.ehdr32.e_ident[EI_DATA] != ELFDATA2LSB)
>           break;