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powerpc/64s: Fix VAS mm use after free

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[ Upstream commit b4bda59b47879cce38a6ec5a01cd3cac702b5331 ]

The refcount on mm is dropped before the coprocessor is detached.

Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Fixes: 7bc6f71bdff5f ("powerpc/vas: Define and use common vas_window struct")
Fixes: b22f2d88e435c ("powerpc/pseries/vas: Integrate API with open/close windows")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230607101024.14559-1-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Nicholas Piggin 2023-06-07 20:10:24 +10:00 committed by Greg Kroah-Hartman
parent 5e79521da1
commit f7d9231300
2 changed files with 2 additions and 2 deletions
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2
arch/powerpc/platforms/powernv/vas-window.c
View File

@ -1310,8 +1310,8 @@ int vas_win_close(struct vas_window *vwin)
/* if send window, drop reference to matching receive window */
if (window->tx_win) {
if (window->user_win) {
put_vas_user_win_ref(&vwin->task_ref);
mm_context_remove_vas_window(vwin->task_ref.mm);
put_vas_user_win_ref(&vwin->task_ref);
}
put_rx_win(window->rxwin);
}

2
arch/powerpc/platforms/pseries/vas.c
View File

@ -441,8 +441,8 @@ static int vas_deallocate_window(struct vas_window *vwin)
atomic_dec(&caps->used_lpar_creds);
mutex_unlock(&vas_pseries_mutex);
put_vas_user_win_ref(&vwin->task_ref);
mm_context_remove_vas_window(vwin->task_ref.mm);
put_vas_user_win_ref(&vwin->task_ref);
kfree(win);
return 0;