linux/mm/kfence
Marco Elver 747c0f35f2 kfence: fix stack trace pruning
Commit b140513524 ("mm/sl[au]b: generalize kmalloc subsystem")
refactored large parts of the kmalloc subsystem, resulting in the stack
trace pruning logic done by KFENCE to no longer work.

While b140513524 attempted to fix the situation by including
'__kmem_cache_free' in the list of functions KFENCE should skip through,
this only works when the compiler actually optimized the tail call from
kfree() to __kmem_cache_free() into a jump (and thus kfree() _not_
appearing in the full stack trace to begin with).

In some configurations, the compiler no longer optimizes the tail call
into a jump, and __kmem_cache_free() appears in the stack trace.  This
means that the pruned stack trace shown by KFENCE would include kfree()
which is not intended - for example:

 | BUG: KFENCE: invalid free in kfree+0x7c/0x120
 |
 | Invalid free of 0xffff8883ed8fefe0 (in kfence-#126):
 |  kfree+0x7c/0x120
 |  test_double_free+0x116/0x1a9
 |  kunit_try_run_case+0x90/0xd0
 | [...]

Fix it by moving __kmem_cache_free() to the list of functions that may be
tail called by an allocator entry function, making the pruning logic work
in both the optimized and unoptimized tail call cases.

Link: https://lkml.kernel.org/r/20221118152216.3914899-1-elver@google.com
Fixes: b140513524 ("mm/sl[au]b: generalize kmalloc subsystem")
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Feng Tang <feng.tang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-22 18:50:44 -08:00
..
.kunitconfig kfence: test: use new suite_{init/exit} support, add .kunitconfig 2022-05-02 12:35:57 -06:00
core.c - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
kfence_test.c Yang Shi has improved the behaviour of khugepaged collapsing of readonly 2022-05-26 12:32:41 -07:00
kfence.h mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
Makefile mm/kfence: remove unnecessary CONFIG_KFENCE option 2022-03-22 15:57:11 -07:00
report.c kfence: fix stack trace pruning 2022-11-22 18:50:44 -08:00