747c0f35f2
Commit b14051352465 ("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 b14051352465 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: b14051352465 ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.