+ lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch added to -mm tree

+ lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch added to -mm tree

[akpm]

The patch titled
     Subject: lib, stackdepot: check stackdepot handle before accessing slabs
has been added to the -mm tree.  Its filename is
     lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch

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------------------------------------------------------
From: Imran Khan <imran.f.khan@oracle.com>
Subject: lib, stackdepot: check stackdepot handle before accessing slabs

Patch series "lib, stackdepot: check stackdepot handle before accessing slabs".

PATCH-1: Checks validity of a stackdepot handle before proceeding to
access stackdepot slab/objects.

PATCH-2: Adds a helper in stackdepot, to allow users to print stack
entries just by specifying the stackdepot handle.  It also changes such
users to use this new interface.  

PATCH-3: Adds a helper in stackdepot, to allow users to print stack
entries into buffers just by specifying the stackdepot handle and
destination buffer.  It also changes such users to use this new interface.


This patch (of 3):

stack_depot_save allocates slabs that will be used for storing objects in
future.If this slab allocation fails we may get to a situation where space
allocation for a new stack_record fails, causing stack_depot_save to
return 0 as handle.  If user of this handle ends up invoking
stack_depot_fetch with this handle value, current implementation of
stack_depot_fetch will end up using slab from wrong index.  To avoid this
check handle value at the beginning.

Link: https://lkml.kernel.org/r/20210915014806.3206938-1-imran.f.khan@oracle.com
Link: https://lkml.kernel.org/r/20210915014806.3206938-2-imran.f.khan@oracle.com
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/stackdepot.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/lib/stackdepot.c~lib-stackdepot-check-stackdepot-handle-before-accessing-slabs
+++ a/lib/stackdepot.c
@@ -232,6 +232,9 @@ unsigned int stack_depot_fetch(depot_sta
 	struct stack_record *stack;
 
 	*entries = NULL;
+	if (!handle)
+		return 0;
+
 	if (parts.slabindex > depot_index) {
 		WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
 			parts.slabindex, depot_index, handle);
_

Patches currently in -mm which might be from imran.f.khan@oracle.com are

lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch
lib-stackdepot-add-helper-to-print-stack-entries.patch
lib-stackdepot-add-helper-to-print-stack-entries-into-buffer.patch