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;
