Re: [PATCH] file: remove the original magic.h

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Sat, 2015-03-28 at 10:36 +0800, Junling Zheng wrote:
> I backport some commits from upstream to fix CVE-2014-9620, and some of them involve the modifying of magic.h.in:
> 
> 90018fe22ff8b74a22fcd142225b0a00f3f12677
> 6ce24f35cd4a43c4bdd249e8e0c4952c1f8eac67
> 0056ec32255de1de973574b0300161a1568767d6
> 09e41625c999a2e5b51e1092f0ef2432a99b5c33
> ce90e05774dd77d86cfc8dfa6da57b32816841c4
> 
> And the final difference between magic.h and magic.h.in is:
> 
> z00238152@Patch-Test:file-5.14>0$ diff -u src/magic.h src/magic.h
> magic.h     magic.h.in
> z00238152@Patch-Test:file-5.14>0$ diff -u src/magic.h src/magic.h.in
> --- src/magic.h	2015-03-28 02:01:46.000000000 +0000
> +++ src/magic.h.in	2015-03-28 02:01:47.000000000 +0000
> @@ -74,7 +74,7 @@
>  #define	MAGIC_NO_CHECK_FORTRAN	0x000000 /* Don't check ascii/fortran */
>  #define	MAGIC_NO_CHECK_TROFF	0x000000 /* Don't check ascii/troff */
> 
> -#define MAGIC_VERSION		514	/* This implementation */
> +#define MAGIC_VERSION		X.YY	/* This implementation */
> 
> 
>  #ifdef __cplusplus
> @@ -100,7 +100,12 @@
>  int magic_list(magic_t, const char *);
>  int magic_errno(magic_t);
> 
> -#define MAGIC_PARAM_MAX_RECURSION	0
> +#define MAGIC_PARAM_INDIR_MAX		0
> +#define MAGIC_PARAM_NAME_MAX		1
> +#define MAGIC_PARAM_ELF_PHNUM_MAX	2
> +#define MAGIC_PARAM_ELF_SHNUM_MAX	3
> +#define MAGIC_PARAM_ELF_NOTES_MAX	4
> +
>  int magic_setparam(magic_t, int, const void *);
>  int magic_getparam(magic_t, int, void *);
> 
> 
> So, if Makefile doesn't generate a new magic.h, there will be some "symbol undeclared" errors during compiling.
> 
> By the way, the upstream code has only magic.h.in, and no magic.h, which only exists in release version tarballs.
> 
> And I think the original magic.h is redundant.

We ran into this problem in our branches. You need to ensure that your
CVE patches just touch magic.h.in and *not* magic.h. If you do that, the
timestamp of magic.h.in will be more recent that magic.h and your build
will function correctly.

The problem is that patch can patch those two files "at the same time"
on fast machines. You should never patch generated filed in patches in
OE in general.

Cheers,

Richard