Re: Linux reports memfd_create() being called without MFD_EXEC or MFD_NOEXEC_SEAL set

[Chet Ramey]

On 4/27/24 6:00 AM, Kerin Millar wrote:
> Hi,
>
> At some point after upgrading to bash-5.3-alpha, the following message appeared 
> in my kernel ring buffer.
>
> [700406.870502] bash[3089019]: memfd_create() called without MFD_EXEC or 
> MFD_NOEXEC_SEAL set
>
> Unfortunately, it took me a while to notice the presence of this message. 
> Therefore, I am uncertain as to what bash was being tasked with at the time 
> that it was logged. The inference of the message seems clear, however. The 
> presently running kernel is 6.6.28.

Bash uses memfd_create to create an anonymous file for noexec command
substitution. It's not clear why it would need file sealing, where
available, in this case.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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