From:   andrey.konovalov@linux.dev
To:     Marco Elver <elver@google.com>,
        Alexander Potapenko <glider@google.com>
Cc:     Andrey Konovalov <andreyknvl@gmail.com>,
        Vlastimil Babka <vbabka@suse.cz>, kasan-dev@googlegroups.com,
        Evgenii Stepanov <eugenis@google.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 01/18] lib/stackdepot: fix setting next_slab_inited in init_stack_slab
Date:   Mon, 30 Jan 2023 21:49:25 +0100
Message-Id: <9fbb4d2bf9b2676a29b120980b5ffbda8e2304ee.1675111415.git.andreyknvl@google.com>
In-Reply-To: <cover.1675111415.git.andreyknvl@google.com>
References: <cover.1675111415.git.andreyknvl@google.com>
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From: Andrey Konovalov <andreyknvl@google.com>

In commit 305e519ce48e ("lib/stackdepot.c: fix global out-of-bounds in
stack_slabs"), init_stack_slab was changed to only use preallocated
memory for the next slab if the slab number limit is not reached.
However, setting next_slab_inited was not moved together with updating
stack_slabs.

Set next_slab_inited only if the preallocated memory was used for the
next slab.

Fixes: 305e519ce48e ("lib/stackdepot.c: fix global out-of-bounds in stack_slabs")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 lib/stackdepot.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 79e894cf8406..0eed9bbcf23e 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -105,12 +105,13 @@ static bool init_stack_slab(void **prealloc)
 		if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) {
 			stack_slabs[depot_index + 1] = *prealloc;
 			*prealloc = NULL;
+			/*
+			 * This smp_store_release pairs with smp_load_acquire()
+			 * from |next_slab_inited| above and in
+			 * stack_depot_save().
+			 */
+			smp_store_release(&next_slab_inited, 1);
 		}
-		/*
-		 * This smp_store_release pairs with smp_load_acquire() from
-		 * |next_slab_inited| above and in stack_depot_save().
-		 */
-		smp_store_release(&next_slab_inited, 1);
 	}
 	return true;
 }
-- 
2.25.1