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SubjectRe: [PATCH BUGFIX] [RESEND] mm: Pass mm->flags as a coredump parameter for consistency
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> 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@redhat.com>
> Cc: Roland McGrath <roland@redhat.com>
> Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

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






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