From: Imran Khan <imran.f.khan@xxxxxxxxxx> Subject: lib, stackdepot: check stackdepot handle before accessing slabs Patch series "lib, stackdepot: check stackdepot handle before accessing slabs", v2. 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/20210915175321.3472770-1-imran.f.khan@xxxxxxxxxx Link: https://lkml.kernel.org/r/20210915014806.3206938-1-imran.f.khan@xxxxxxxxxx Link: https://lkml.kernel.org/r/20210915014806.3206938-2-imran.f.khan@xxxxxxxxxx Signed-off-by: Imran Khan <imran.f.khan@xxxxxxxxxx> Suggested-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Cc: Maxime Ripard <mripard@xxxxxxxxxx> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> Cc: David Airlie <airlied@xxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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 @@ -231,6 +231,9 @@ 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); _
