This is a note to let you know that I've just added the patch titled powerpc/64s: Fix VAS mm use after free to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-64s-fix-vas-mm-use-after-free.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f52ca4f5e116c06793936c44c6604a1facfbe464 Author: Nicholas Piggin <npiggin@xxxxxxxxx> Date: Wed Jun 7 20:10:24 2023 +1000 powerpc/64s: Fix VAS mm use after free [ Upstream commit b4bda59b47879cce38a6ec5a01cd3cac702b5331 ] The refcount on mm is dropped before the coprocessor is detached. Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxx> 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@xxxxxxxxx> Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://msgid.link/20230607101024.14559-1-npiggin@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c index 0072682531d80..b664838008c12 100644 --- a/arch/powerpc/platforms/powernv/vas-window.c +++ b/arch/powerpc/platforms/powernv/vas-window.c @@ -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); } diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c index 15046d80f0427..b54f6fc27896f 100644 --- a/arch/powerpc/platforms/pseries/vas.c +++ b/arch/powerpc/platforms/pseries/vas.c @@ -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;