]> git.ipfire.org Git - thirdparty/linux.git/commit
MIPS: Don't crash in stack_top() for tasks without ABI or vDSO
authorThomas Weißschuh <thomas.weissschuh@linutronix.de>
Wed, 11 Jun 2025 11:28:26 +0000 (13:28 +0200)
committerThomas Bogendoerfer <tsbogend@alpha.franken.de>
Thu, 3 Jul 2025 10:35:11 +0000 (12:35 +0200)
commite9f4a6b3421e936c3ee9d74710243897d74dbaa2
treeb42071f29f80f1e12552d628ce6f11b3c9eb69f8
parentda1fe323261f6a3e1a959e59c24f86186e8a9f4f
MIPS: Don't crash in stack_top() for tasks without ABI or vDSO

Not all tasks have an ABI associated or vDSO mapped,
for example kthreads never do.
If such a task ever ends up calling stack_top(), it will derefence the
NULL ABI pointer and crash.

This can for example happen when using kunit:

    mips_stack_top+0x28/0xc0
    arch_pick_mmap_layout+0x190/0x220
    kunit_vm_mmap_init+0xf8/0x138
    __kunit_add_resource+0x40/0xa8
    kunit_vm_mmap+0x88/0xd8
    usercopy_test_init+0xb8/0x240
    kunit_try_run_case+0x5c/0x1a8
    kunit_generic_run_threadfn_adapter+0x28/0x50
    kthread+0x118/0x240
    ret_from_kernel_thread+0x14/0x1c

Only dereference the ABI point if it is set.

The GIC page is also included as it is specific to the vDSO.
Also move the randomization adjustment into the same conditional.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
arch/mips/kernel/process.c