orangefs: fix double-free of trailer_buf on readdir copy failure

On a readdir downcall, orangefs_devreq_write_iter() frees
op->downcall.trailer_buf with vfree() when copy_from_iter_full() fails,
but does not clear the pointer before goto Efault. The waiter in
do_readdir() is then woken with a negative status and frees the same
pointer again on its r < 0 path, causing a deterministic double-free.
A client holding /dev/pvfs2-req triggers it by sending a readdir
downcall whose declared trailer_size exceeds the bytes it supplies.

Clear the pointer after freeing so the readdir-side vfree() becomes a
no-op.

Fixes: 382f4581e67f ("orangefs: rewrite readdir to fix several bugs")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Yifei Gao <gyf161023@gmail.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

0 files changed, 0 insertions, 0 deletions