Commit 305e519c authored Feb 20, 2020 by Alexander Potapenko Committed by Linus Torvalds Feb 21, 2020

lib/stackdepot.c: fix global out-of-bounds in stack_slabs

Walter Wu has reported a potential case in which init_stack_slab() is
called after stack_slabs[STACK_ALLOC_MAX_SLABS - 1] has already been
initialized.  In that case init_stack_slab() will overwrite
stack_slabs[STACK_ALLOC_MAX_SLABS], which may result in a memory
corruption.

Link: http://lkml.kernel.org/r/20200218102950.260263-1-glider@google.com


Fixes: cd11016e ("mm, kasan: stackdepot implementation. Enable stackdepot for SLAB")
Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: Walter Wu <walter-zh.wu@mediatek.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 18e19f19

lib/stackdepot.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -83,15 +83,19 @@ static bool init_stack_slab(void **prealloc)
		return true;
		if (stack_slabs[depot_index] == NULL) {
		stack_slabs[depot_index] = *prealloc;
		*prealloc = NULL;
		} else {
		/* If this is the last depot slab, do not touch the next one. */
		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);
		}
		*prealloc = NULL;
		return true;
		}

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