[U-Boot] [PATCH v2] bootm: Avoid 256-byte overflow in fixup_silent_linux()

[Wolfgang Denk]

Dear Doug Anderson,

In message <1319133298-30249-1-git-send-email-dianders at chromium.org> you wrote:
> This makes fixup_silent_linux() use malloc() to allocate its
> working space, meaning that our maximum kernel command line
> should only be limited by malloc().  Previously it was silently
> overflowing the stack.
...
>  static void fixup_silent_linux(void)
>  {
> -	char buf[256], *start, *end;

Are you sure that the kernel's buffer is long enough?

For example on PowerPC, there is a current hard limit on 512
characters:

	arch/powerpc/boot/ops.h:#define COMMAND_LINE_SIZE       512
	arch/powerpc/kernel/setup-common.c:char cmd_line[COMMAND_LINE_SIZE];

On SPARC, we have 256 bytes hard limit, see arch/sparc/prom/bootstr_64.c:

	#define BARG_LEN  256
	...
	prom_getstring(prom_chosen_node, "bootargs",
			bootstr_info.bootstr_buf, BARG_LEN);

And so on for other architectures, for example:

arch/score/include/asm/setup.h:#define COMMAND_LINE_SIZE        256

arch/m68k/include/asm/setup.h:#define COMMAND_LINE_SIZE 256

arch/avr32/include/asm/setup.h:#define COMMAND_LINE_SIZE 256

arch/microblaze/include/asm/setup.h:#define COMMAND_LINE_SIZE   256

arch/mn10300/include/asm/param.h:#define COMMAND_LINE_SIZE 256

arch/sparc/include/asm/setup.h:# define COMMAND_LINE_SIZE 256

arch/cris/include/asm/setup.h:#define COMMAND_LINE_SIZE 256

arch/xtensa/include/asm/setup.h:#define COMMAND_LINE_SIZE       256

arch/alpha/include/asm/setup.h:#define COMMAND_LINE_SIZE        256


I think your patch is likely to break all these architectures?


Best regards,

Wolfgang Denk

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