svn commit: r327684 - in head/sys/compat: cloudabi32 cloudabi64

[Brooks Davis]

On Mon, Jan 08, 2018 at 04:13:42PM +0100, Ed Schouten wrote:
> Hi Andrew,
> 
> 2018-01-08 8:37 GMT+01:00 Andrew Turner <andrew at fubar.geek.nz>:
> > Won???t this lead to a NULL pointer dereference on overflow? mallocarray can return NULL even with M_WAITOK.
> 
> Yes, it will, but an overflow shouldn't happen in the first place.
> ri_data_len is compared with UIO_MAXIOV a few lines above. Even if an
> overflow would happen, this would cause a kernel panic due to a NULL
> pointer dereference later on, which is likely easier to debug than
> some piece of code that overruns a buffer.

Given that the overflow is due to a bug, there's an argument we should
panic rather than returning NULL even in the M_NOWAIT case so we produce
a useful message in exactly the right place.

-- Brooks
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