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authorAlexander Potapenko <glider@google.com>2020-04-06 20:10:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:43 -0700
commit69866e156ce28c47dc0085b5ba5e734f5511812e (patch)
tree308cd68d44e5d09c827bc43d5a200b8ba896d3ea /lib
parent9cf016e6b49b53d6c15d4137c034178148149ef4 (diff)
lib/stackdepot.c: check depot_index before accessing the stack slab
Avoid crashes on corrupted stack ids. Despite stack ID corruption may indicate other bugs in the program, we'd better fail gracefully on such IDs instead of crashing the kernel. This patch has been previously mailed as part of KMSAN RFC patch series. Link: http://lkml.kernel.org/r/20200220141916.55455-1-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Marco Elver <elver@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> From: Dan Carpenter <dan.carpenter@oracle.com> Subject: lib/stackdepot.c: fix a condition in stack_depot_fetch() We should check for a NULL pointer first before adding the offset. Otherwise if the pointer is NULL and the offset is non-zero, it will lead to an Oops. Fixes: d45048e65a59 ("lib/stackdepot.c: check depot_index before accessing the stack slab") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Alexander Potapenko <glider@google.com> Link: http://lkml.kernel.org/r/20200312113006.GA20562@mwanda Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/stackdepot.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 81c69c08d1d1..1ec36ee344e0 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -202,9 +202,20 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries)
{
union handle_parts parts = { .handle = handle };
- void *slab = stack_slabs[parts.slabindex];
+ void *slab;
size_t offset = parts.offset << STACK_ALLOC_ALIGN;
- struct stack_record *stack = slab + offset;
+ struct stack_record *stack;
+
+ *entries = NULL;
+ if (parts.slabindex > depot_index) {
+ WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
+ parts.slabindex, depot_index, handle);
+ return 0;
+ }
+ slab = stack_slabs[parts.slabindex];
+ if (!slab)
+ return 0;
+ stack = slab + offset;
*entries = stack->entries;
return stack->size;