From ecbe2aea0a58780aa992843bb1abcfce37700481 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Date: Thu, 7 Nov 2024 15:24:00 +0800 Subject: [PATCH] LoongArch: Don't crash in stack_top() for tasks without vDSO MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit stable inclusion from stable-v6.6.58 commit a94c197d4d749954dfaa37e907fcc8c04e4aad7e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB2BWS CVE: CVE-2024-50133 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a94c197d4d749954dfaa37e907fcc8c04e4aad7e --------------------------- [ Upstream commit 134475a9ab8487527238d270639a8cb74c10aab2 ] 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 Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin Conflicts: arch/loongarch/kernel/process.c [fix context conflicts] Signed-off-by: Lin Yujun --- arch/loongarch/kernel/process.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c index f6c0bdb0238b..92f336cbd51e 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -280,13 +280,15 @@ unsigned long stack_top(void) { unsigned long top = TASK_SIZE & PAGE_MASK; + if (current->thread.vdso) { /* Space for the VDSO & data page */ top -= PAGE_ALIGN(current->thread.vdso->size); top -= PAGE_SIZE; /* Space to randomize the VDSO base */ if (current->flags & PF_RANDOMIZE) - top -= VDSO_RANDOMIZE_SIZE; + top -= VDSO_RANDOMIZE_SIZE; + } return top; } -- Gitee