diff options
| author | Thomas Weißschuh <thomas.weissschuh@linutronix.de> | 2024-10-21 17:11:19 +0300 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2024-10-21 17:11:19 +0300 |
| commit | 134475a9ab8487527238d270639a8cb74c10aab2 (patch) | |
| tree | 15f40b044bcd600d8ea6dbce51cfd06e779bf445 | |
| parent | 2ed119aef60d73d00371195fc84dd68248071100 (diff) | |
| download | linux-134475a9ab8487527238d270639a8cb74c10aab2.tar.xz | |
LoongArch: Don't crash in stack_top() for tasks without vDSO
Not all tasks have a vDSO mapped, for example kthreads never do. If such
a task ever ends up calling stack_top(), it will derefence the NULL vdso
pointer and crash.
This can for example happen when using kunit:
[<9000000000203874>] stack_top+0x58/0xa8
[<90000000002956cc>] arch_pick_mmap_layout+0x164/0x220
[<90000000003c284c>] kunit_vm_mmap_init+0x108/0x12c
[<90000000003c1fbc>] __kunit_add_resource+0x38/0x8c
[<90000000003c2704>] kunit_vm_mmap+0x88/0xc8
[<9000000000410b14>] usercopy_test_init+0xbc/0x25c
[<90000000003c1db4>] kunit_try_run_case+0x5c/0x184
[<90000000003c3d54>] kunit_generic_run_threadfn_adapter+0x24/0x48
[<900000000022e4bc>] kthread+0xc8/0xd4
[<9000000000200ce8>] ret_from_kernel_thread+0xc/0xa4
Fixes: 803b0fc5c3f2 ("LoongArch: Add process management")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
| -rw-r--r-- | arch/loongarch/kernel/process.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c index f2ff8b5d591e..6e58f65455c7 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -293,13 +293,15 @@ unsigned long stack_top(void) { unsigned long top = TASK_SIZE & PAGE_MASK; - /* Space for the VDSO & data page */ - top -= PAGE_ALIGN(current->thread.vdso->size); - top -= VVAR_SIZE; - - /* Space to randomize the VDSO base */ - if (current->flags & PF_RANDOMIZE) - top -= VDSO_RANDOMIZE_SIZE; + if (current->thread.vdso) { + /* Space for the VDSO & data page */ + top -= PAGE_ALIGN(current->thread.vdso->size); + top -= VVAR_SIZE; + + /* Space to randomize the VDSO base */ + if (current->flags & PF_RANDOMIZE) + top -= VDSO_RANDOMIZE_SIZE; + } return top; } |