Re: [PATCH BUGFIX] [RESEND] mm: Pass mm->flags as a coredump parameter for consistency

[KOSAKI Motohiro]

> Pass mm->flags as a coredump parameter for consistency.
> 
>  ---
> 1787         if (mm->core_state || !get_dumpable(mm)) {  <- (1)
> 1788                 up_write(&mm->mmap_sem);
> 1789                 put_cred(cred);
> 1790                 goto fail;
> 1791         }
> 1792
> [...]
> 1798         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */ <-(2)
> 1799                 flag = O_EXCL;          /* Stop rewrite attacks */
> 1800                 cred->fsuid = 0;        /* Dump root private */
> 1801         }
>  ---
> 
> Since dumpable bits are not protected by lock, there is a
> chance to change these bits between (1) and (2).
> 
> To solve this issue, this patch copies mm->flags to
> coredump_params.mm_flags at the beginning of do_coredump()                      and uses it instead of get_dumpable() while dumping core.
> 
> This copy is also passed to binfmt->core_dump, since
> elf*_core_dump() uses dump_filter bits in mm->flags.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Roland McGrath <roland@xxxxxxxxxx>
> Cc: Hidehiro Kawai <hidehiro.kawai.ez@xxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>

looks good to me.
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>




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