[PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork

[PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork

[Jisheng Zhang]

Testing tools/testing/selftests/timens/vfork_exec.c got below
kernel log:

[    6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020
[    6.842255] Oops [#1]
[    6.842871] Modules linked in:
[    6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8
[    6.845861] Hardware name: riscv-virtio,qemu (DT)
[    6.848009] epc : vdso_join_timens+0xd2/0x110
[    6.850097]  ra : vdso_join_timens+0xd2/0x110
[    6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0
[    6.852562]  gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030
[    6.853852]  t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40
[    6.854984]  s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c
[    6.856221]  a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000
[    6.858114]  a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
[    6.859484]  s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000
[    6.860751]  s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38
[    6.862029]  s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e
[    6.863304]  s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f
[    6.864565]  t5 : ffffffff80d11130 t6 : ff6000000181fa00
[    6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d
[    6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a
[    6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4
[    6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0
[    6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214
[    6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4
[    6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee
[    6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48
[    6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2
[    6.877484] ---[ end trace 0000000000000000 ]---

This is because the mm->context.vdso_info is NULL in vfork case. From
another side, mm->context.vdso_info either points to vdso info
for RV64 or vdso info for compat, there's no need to bloat riscv's
mm_context_t, we can handle the difference when setup the additional
page for vdso.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation")
---

since v1:
 - add "Fixes" tag
 - fix build error when CONFIG_COMPAT is enabled.

 arch/riscv/include/asm/mmu.h |   1 -
 arch/riscv/kernel/vdso.c     | 178 +++++++++++++++++++----------------
 2 files changed, 95 insertions(+), 84 deletions(-)

diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
index cedcf8ea3c76..0099dc116168 100644
--- a/arch/riscv/include/asm/mmu.h
+++ b/arch/riscv/include/asm/mmu.h
@@ -16,7 +16,6 @@ typedef struct {
 	atomic_long_t id;
 #endif
 	void *vdso;
-	void *vdso_info;
 #ifdef CONFIG_SMP
 	/* A local icache flush is needed before user execution can resume. */
 	cpumask_t icache_stale_mask;
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index 69b05b6c181b..8ca3b821e1b5 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -27,6 +27,11 @@ extern char vdso_start[], vdso_end[];
 extern char compat_vdso_start[], compat_vdso_end[];
 #endif
 
+enum vdso_abi {
+	VDSO_ABI_RV64,
+	VDSO_ABI_RV32,
+};
+
 enum vvar_pages {
 	VVAR_DATA_PAGE_OFFSET,
 	VVAR_TIMENS_PAGE_OFFSET,
@@ -68,67 +73,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
-static void __init __vdso_init(struct __vdso_info *vdso_info)
-{
-	unsigned int i;
-	struct page **vdso_pagelist;
-	unsigned long pfn;
-
-	if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
-		panic("vDSO is not a valid ELF object!\n");
-
-	vdso_info->vdso_pages = (
-		vdso_info->vdso_code_end -
-		vdso_info->vdso_code_start) >>
-		PAGE_SHIFT;
-
-	vdso_pagelist = kcalloc(vdso_info->vdso_pages,
-				sizeof(struct page *),
-				GFP_KERNEL);
-	if (vdso_pagelist == NULL)
-		panic("vDSO kcalloc failed!\n");
-
-	/* Grab the vDSO code pages. */
-	pfn = sym_to_pfn(vdso_info->vdso_code_start);
-
-	for (i = 0; i < vdso_info->vdso_pages; i++)
-		vdso_pagelist[i] = pfn_to_page(pfn + i);
-
-	vdso_info->cm->pages = vdso_pagelist;
-}
-
 #ifdef CONFIG_TIME_NS
-struct vdso_data *arch_get_vdso_data(void *vvar_page)
-{
-	return (struct vdso_data *)(vvar_page);
-}
-
-/*
- * The vvar mapping contains data for a specific time namespace, so when a task
- * changes namespace we must unmap its vvar data for the old namespace.
- * Subsequent faults will map in data for the new namespace.
- *
- * For more details see timens_setup_vdso_data().
- */
-int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
-{
-	struct mm_struct *mm = task->mm;
-	struct vm_area_struct *vma;
-	struct __vdso_info *vdso_info = mm->context.vdso_info;
-
-	mmap_read_lock(mm);
-
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		unsigned long size = vma->vm_end - vma->vm_start;
-
-		if (vma_is_special_mapping(vma, vdso_info->dm))
-			zap_page_range(vma, vma->vm_start, size);
-	}
-
-	mmap_read_unlock(mm);
-	return 0;
-}
-
 static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
 {
 	if (likely(vma->vm_mm == current->mm))
@@ -197,13 +142,6 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
 	},
 };
 
-static struct __vdso_info vdso_info __ro_after_init = {
-	.name = "vdso",
-	.vdso_code_start = vdso_start,
-	.vdso_code_end = vdso_end,
-	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
-	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
-};
 
 #ifdef CONFIG_COMPAT
 static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
@@ -216,21 +154,97 @@ static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
 		.mremap = vdso_mremap,
 	},
 };
+#endif
 
-static struct __vdso_info compat_vdso_info __ro_after_init = {
-	.name = "compat_vdso",
-	.vdso_code_start = compat_vdso_start,
-	.vdso_code_end = compat_vdso_end,
-	.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
-	.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
+static struct __vdso_info vdso_info[] __ro_after_init = {
+	[VDSO_ABI_RV64] = {
+		.name = "vdso",
+		.vdso_code_start = vdso_start,
+		.vdso_code_end = vdso_end,
+		.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
+		.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
+	},
+#ifdef CONFIG_COMPAT
+	[VDSO_ABI_RV32] = {
+		.name = "compat_vdso",
+		.vdso_code_start = compat_vdso_start,
+		.vdso_code_end = compat_vdso_end,
+		.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
+		.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
+	},
+#endif
 };
+
+static void __init __vdso_init(enum vdso_abi abi)
+{
+	unsigned int i;
+	struct page **vdso_pagelist;
+	unsigned long pfn;
+
+	if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4))
+		panic("vDSO is not a valid ELF object!\n");
+
+	vdso_info[abi].vdso_pages = (
+		vdso_info[abi].vdso_code_end -
+		vdso_info[abi].vdso_code_start) >>
+		PAGE_SHIFT;
+
+	vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages,
+				sizeof(struct page *),
+				GFP_KERNEL);
+	if (vdso_pagelist == NULL)
+		panic("vDSO kcalloc failed!\n");
+
+	/* Grab the vDSO code pages. */
+	pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
+
+	for (i = 0; i < vdso_info[abi].vdso_pages; i++)
+		vdso_pagelist[i] = pfn_to_page(pfn + i);
+
+	vdso_info[abi].cm->pages = vdso_pagelist;
+}
+
+#ifdef CONFIG_TIME_NS
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+	return (struct vdso_data *)(vvar_page);
+}
+
+/*
+ * The vvar mapping contains data for a specific time namespace, so when a task
+ * changes namespace we must unmap its vvar data for the old namespace.
+ * Subsequent faults will map in data for the new namespace.
+ *
+ * For more details see timens_setup_vdso_data().
+ */
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+	struct mm_struct *mm = task->mm;
+	struct vm_area_struct *vma;
+
+	mmap_read_lock(mm);
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		unsigned long size = vma->vm_end - vma->vm_start;
+
+		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV64].dm))
+			zap_page_range(vma, vma->vm_start, size);
+#ifdef CONFIG_COMPAT
+		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV32].dm))
+			zap_page_range(vma, vma->vm_start, size);
+#endif
+	}
+
+	mmap_read_unlock(mm);
+	return 0;
+}
 #endif
 
 static int __init vdso_init(void)
 {
-	__vdso_init(&vdso_info);
+	__vdso_init(VDSO_ABI_RV64);
 #ifdef CONFIG_COMPAT
-	__vdso_init(&compat_vdso_info);
+	__vdso_init(VDSO_ABI_RV32);
 #endif
 
 	return 0;
@@ -240,14 +254,14 @@ arch_initcall(vdso_init);
 static int __setup_additional_pages(struct mm_struct *mm,
 				    struct linux_binprm *bprm,
 				    int uses_interp,
-				    struct __vdso_info *vdso_info)
+				    enum vdso_abi abi)
 {
 	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 	void *ret;
 
 	BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
 
-	vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
+	vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
 	/* Be sure to map the data page */
 	vdso_mapping_len = vdso_text_len + VVAR_SIZE;
 
@@ -258,18 +272,17 @@ static int __setup_additional_pages(struct mm_struct *mm,
 	}
 
 	ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
-		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
+		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info[abi].dm);
 	if (IS_ERR(ret))
 		goto up_fail;
 
 	vdso_base += VVAR_SIZE;
 	mm->context.vdso = (void *)vdso_base;
-	mm->context.vdso_info = (void *)vdso_info;
 
 	ret =
 	   _install_special_mapping(mm, vdso_base, vdso_text_len,
 		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
-		vdso_info->cm);
+		vdso_info[abi].cm);
 
 	if (IS_ERR(ret))
 		goto up_fail;
@@ -291,8 +304,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
 
-	ret = __setup_additional_pages(mm, bprm, uses_interp,
-							&compat_vdso_info);
+	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV32);
 	mmap_write_unlock(mm);
 
 	return ret;
@@ -307,7 +319,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
 
-	ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
+	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV64);
 	mmap_write_unlock(mm);
 
 	return ret;
-- 
2.34.1


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Re: [PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork

[Guo Ren]

Great job! I've tested it on rv32-rootfs, and everything seems to be working.

Tested-by: Guo Ren <guoren@kernel.org>

On Thu, Sep 8, 2022 at 11:13 PM Jisheng Zhang <jszhang@kernel.org> wrote:
>
> Testing tools/testing/selftests/timens/vfork_exec.c got below
> kernel log:
>
> [    6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020
> [    6.842255] Oops [#1]
> [    6.842871] Modules linked in:
> [    6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8
> [    6.845861] Hardware name: riscv-virtio,qemu (DT)
> [    6.848009] epc : vdso_join_timens+0xd2/0x110
> [    6.850097]  ra : vdso_join_timens+0xd2/0x110
> [    6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0
> [    6.852562]  gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030
> [    6.853852]  t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40
> [    6.854984]  s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c
> [    6.856221]  a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000
> [    6.858114]  a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
> [    6.859484]  s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000
> [    6.860751]  s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38
> [    6.862029]  s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e
> [    6.863304]  s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f
> [    6.864565]  t5 : ffffffff80d11130 t6 : ff6000000181fa00
> [    6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d
> [    6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a
> [    6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4
> [    6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0
> [    6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214
> [    6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4
> [    6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee
> [    6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48
> [    6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2
> [    6.877484] ---[ end trace 0000000000000000 ]---
>
> This is because the mm->context.vdso_info is NULL in vfork case. From
> another side, mm->context.vdso_info either points to vdso info
> for RV64 or vdso info for compat, there's no need to bloat riscv's
> mm_context_t, we can handle the difference when setup the additional
> page for vdso.
>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation")
> ---
>
> since v1:
>  - add "Fixes" tag
>  - fix build error when CONFIG_COMPAT is enabled.
>
>  arch/riscv/include/asm/mmu.h |   1 -
>  arch/riscv/kernel/vdso.c     | 178 +++++++++++++++++++----------------
>  2 files changed, 95 insertions(+), 84 deletions(-)
>
> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> index cedcf8ea3c76..0099dc116168 100644
> --- a/arch/riscv/include/asm/mmu.h
> +++ b/arch/riscv/include/asm/mmu.h
> @@ -16,7 +16,6 @@ typedef struct {
>         atomic_long_t id;
>  #endif
>         void *vdso;
> -       void *vdso_info;
>  #ifdef CONFIG_SMP
>         /* A local icache flush is needed before user execution can resume. */
>         cpumask_t icache_stale_mask;
> diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
> index 69b05b6c181b..8ca3b821e1b5 100644
> --- a/arch/riscv/kernel/vdso.c
> +++ b/arch/riscv/kernel/vdso.c
> @@ -27,6 +27,11 @@ extern char vdso_start[], vdso_end[];
>  extern char compat_vdso_start[], compat_vdso_end[];
>  #endif
>
> +enum vdso_abi {
> +       VDSO_ABI_RV64,
> +       VDSO_ABI_RV32,
> +};
> +
>  enum vvar_pages {
>         VVAR_DATA_PAGE_OFFSET,
>         VVAR_TIMENS_PAGE_OFFSET,
> @@ -68,67 +73,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
>         return 0;
>  }
>
> -static void __init __vdso_init(struct __vdso_info *vdso_info)
> -{
> -       unsigned int i;
> -       struct page **vdso_pagelist;
> -       unsigned long pfn;
> -
> -       if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
> -               panic("vDSO is not a valid ELF object!\n");
> -
> -       vdso_info->vdso_pages = (
> -               vdso_info->vdso_code_end -
> -               vdso_info->vdso_code_start) >>
> -               PAGE_SHIFT;
> -
> -       vdso_pagelist = kcalloc(vdso_info->vdso_pages,
> -                               sizeof(struct page *),
> -                               GFP_KERNEL);
> -       if (vdso_pagelist == NULL)
> -               panic("vDSO kcalloc failed!\n");
> -
> -       /* Grab the vDSO code pages. */
> -       pfn = sym_to_pfn(vdso_info->vdso_code_start);
> -
> -       for (i = 0; i < vdso_info->vdso_pages; i++)
> -               vdso_pagelist[i] = pfn_to_page(pfn + i);
> -
> -       vdso_info->cm->pages = vdso_pagelist;
> -}
> -
>  #ifdef CONFIG_TIME_NS
> -struct vdso_data *arch_get_vdso_data(void *vvar_page)
> -{
> -       return (struct vdso_data *)(vvar_page);
> -}
> -
> -/*
> - * The vvar mapping contains data for a specific time namespace, so when a task
> - * changes namespace we must unmap its vvar data for the old namespace.
> - * Subsequent faults will map in data for the new namespace.
> - *
> - * For more details see timens_setup_vdso_data().
> - */
> -int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> -{
> -       struct mm_struct *mm = task->mm;
> -       struct vm_area_struct *vma;
> -       struct __vdso_info *vdso_info = mm->context.vdso_info;
> -
> -       mmap_read_lock(mm);
> -
> -       for (vma = mm->mmap; vma; vma = vma->vm_next) {
> -               unsigned long size = vma->vm_end - vma->vm_start;
> -
> -               if (vma_is_special_mapping(vma, vdso_info->dm))
> -                       zap_page_range(vma, vma->vm_start, size);
> -       }
> -
> -       mmap_read_unlock(mm);
> -       return 0;
> -}
> -
>  static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
>  {
>         if (likely(vma->vm_mm == current->mm))
> @@ -197,13 +142,6 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
>         },
>  };
>
> -static struct __vdso_info vdso_info __ro_after_init = {
> -       .name = "vdso",
> -       .vdso_code_start = vdso_start,
> -       .vdso_code_end = vdso_end,
> -       .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> -       .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> -};
>
>  #ifdef CONFIG_COMPAT
>  static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
> @@ -216,21 +154,97 @@ static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
>                 .mremap = vdso_mremap,
>         },
>  };
> +#endif
>
> -static struct __vdso_info compat_vdso_info __ro_after_init = {
> -       .name = "compat_vdso",
> -       .vdso_code_start = compat_vdso_start,
> -       .vdso_code_end = compat_vdso_end,
> -       .dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> -       .cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> +static struct __vdso_info vdso_info[] __ro_after_init = {
> +       [VDSO_ABI_RV64] = {
> +               .name = "vdso",
> +               .vdso_code_start = vdso_start,
> +               .vdso_code_end = vdso_end,
> +               .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> +               .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> +       },
> +#ifdef CONFIG_COMPAT
> +       [VDSO_ABI_RV32] = {
> +               .name = "compat_vdso",
> +               .vdso_code_start = compat_vdso_start,
> +               .vdso_code_end = compat_vdso_end,
> +               .dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> +               .cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> +       },
> +#endif
>  };
> +
> +static void __init __vdso_init(enum vdso_abi abi)
> +{
> +       unsigned int i;
> +       struct page **vdso_pagelist;
> +       unsigned long pfn;
> +
> +       if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4))
> +               panic("vDSO is not a valid ELF object!\n");
> +
> +       vdso_info[abi].vdso_pages = (
> +               vdso_info[abi].vdso_code_end -
> +               vdso_info[abi].vdso_code_start) >>
> +               PAGE_SHIFT;
> +
> +       vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages,
> +                               sizeof(struct page *),
> +                               GFP_KERNEL);
> +       if (vdso_pagelist == NULL)
> +               panic("vDSO kcalloc failed!\n");
> +
> +       /* Grab the vDSO code pages. */
> +       pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
> +
> +       for (i = 0; i < vdso_info[abi].vdso_pages; i++)
> +               vdso_pagelist[i] = pfn_to_page(pfn + i);
> +
> +       vdso_info[abi].cm->pages = vdso_pagelist;
> +}
> +
> +#ifdef CONFIG_TIME_NS
> +struct vdso_data *arch_get_vdso_data(void *vvar_page)
> +{
> +       return (struct vdso_data *)(vvar_page);
> +}
> +
> +/*
> + * The vvar mapping contains data for a specific time namespace, so when a task
> + * changes namespace we must unmap its vvar data for the old namespace.
> + * Subsequent faults will map in data for the new namespace.
> + *
> + * For more details see timens_setup_vdso_data().
> + */
> +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> +{
> +       struct mm_struct *mm = task->mm;
> +       struct vm_area_struct *vma;
> +
> +       mmap_read_lock(mm);
> +
> +       for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +               unsigned long size = vma->vm_end - vma->vm_start;
> +
> +               if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV64].dm))
> +                       zap_page_range(vma, vma->vm_start, size);
> +#ifdef CONFIG_COMPAT
> +               if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV32].dm))
> +                       zap_page_range(vma, vma->vm_start, size);
> +#endif
> +       }
> +
> +       mmap_read_unlock(mm);
> +       return 0;
> +}
>  #endif
>
>  static int __init vdso_init(void)
>  {
> -       __vdso_init(&vdso_info);
> +       __vdso_init(VDSO_ABI_RV64);
>  #ifdef CONFIG_COMPAT
> -       __vdso_init(&compat_vdso_info);
> +       __vdso_init(VDSO_ABI_RV32);
>  #endif
>
>         return 0;
> @@ -240,14 +254,14 @@ arch_initcall(vdso_init);
>  static int __setup_additional_pages(struct mm_struct *mm,
>                                     struct linux_binprm *bprm,
>                                     int uses_interp,
> -                                   struct __vdso_info *vdso_info)
> +                                   enum vdso_abi abi)
>  {
>         unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
>         void *ret;
>
>         BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
>
> -       vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
> +       vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
>         /* Be sure to map the data page */
>         vdso_mapping_len = vdso_text_len + VVAR_SIZE;
>
> @@ -258,18 +272,17 @@ static int __setup_additional_pages(struct mm_struct *mm,
>         }
>
>         ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
> -               (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
> +               (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info[abi].dm);
>         if (IS_ERR(ret))
>                 goto up_fail;
>
>         vdso_base += VVAR_SIZE;
>         mm->context.vdso = (void *)vdso_base;
> -       mm->context.vdso_info = (void *)vdso_info;
>
>         ret =
>            _install_special_mapping(mm, vdso_base, vdso_text_len,
>                 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
> -               vdso_info->cm);
> +               vdso_info[abi].cm);
>
>         if (IS_ERR(ret))
>                 goto up_fail;
> @@ -291,8 +304,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
>         if (mmap_write_lock_killable(mm))
>                 return -EINTR;
>
> -       ret = __setup_additional_pages(mm, bprm, uses_interp,
> -                                                       &compat_vdso_info);
> +       ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV32);
>         mmap_write_unlock(mm);
>
>         return ret;
> @@ -307,7 +319,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
>         if (mmap_write_lock_killable(mm))
>                 return -EINTR;
>
> -       ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
> +       ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV64);
>         mmap_write_unlock(mm);
>
>         return ret;
> --
> 2.34.1
>


-- 
Best Regards
 Guo Ren

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Re: [PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork

[Palmer Dabbelt]

On Thu, 08 Sep 2022 08:04:21 PDT (-0700), jszhang@kernel.org wrote:
> Testing tools/testing/selftests/timens/vfork_exec.c got below
> kernel log:
>
> [    6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020
> [    6.842255] Oops [#1]
> [    6.842871] Modules linked in:
> [    6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8
> [    6.845861] Hardware name: riscv-virtio,qemu (DT)
> [    6.848009] epc : vdso_join_timens+0xd2/0x110
> [    6.850097]  ra : vdso_join_timens+0xd2/0x110
> [    6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0
> [    6.852562]  gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030
> [    6.853852]  t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40
> [    6.854984]  s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c
> [    6.856221]  a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000
> [    6.858114]  a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
> [    6.859484]  s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000
> [    6.860751]  s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38
> [    6.862029]  s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e
> [    6.863304]  s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f
> [    6.864565]  t5 : ffffffff80d11130 t6 : ff6000000181fa00
> [    6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d
> [    6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a
> [    6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4
> [    6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0
> [    6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214
> [    6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4
> [    6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee
> [    6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48
> [    6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2
> [    6.877484] ---[ end trace 0000000000000000 ]---
>
> This is because the mm->context.vdso_info is NULL in vfork case. From
> another side, mm->context.vdso_info either points to vdso info
> for RV64 or vdso info for compat, there's no need to bloat riscv's
> mm_context_t, we can handle the difference when setup the additional
> page for vdso.

Makes sense, but I think there's a lot more diff here than we need in 
order to just fix the bug.  Does something like the following still fix 
it?  Also at kernel.org/palmer/vdso-fix-v3 .  Maybe it's a bit pedantic 
, but this late in the cycle with everyone traveling I'd prefer to keep 
the fixes smaller when possible.

diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
index cedcf8ea3c76..0099dc116168 100644
--- a/arch/riscv/include/asm/mmu.h
+++ b/arch/riscv/include/asm/mmu.h
@@ -16,7 +16,6 @@ typedef struct {
 	atomic_long_t id;
 #endif
 	void *vdso;
-	void *vdso_info;
 #ifdef CONFIG_SMP
 	/* A local icache flush is needed before user execution can resume. */
 	cpumask_t icache_stale_mask;
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index 69b05b6c181b..58b8d73a4b1f 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -23,8 +23,10 @@ struct vdso_data {
 #endif

 extern char vdso_start[], vdso_end[];
+static struct __vdso_info vdso_info;
 #ifdef CONFIG_COMPAT
 extern char compat_vdso_start[], compat_vdso_end[];
+static struct __vdso_info compat_vdso_info;
 #endif

 enum vvar_pages {
@@ -114,15 +116,18 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
 {
 	struct mm_struct *mm = task->mm;
 	struct vm_area_struct *vma;
-	struct __vdso_info *vdso_info = mm->context.vdso_info;

 	mmap_read_lock(mm);

 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 		unsigned long size = vma->vm_end - vma->vm_start;

-		if (vma_is_special_mapping(vma, vdso_info->dm))
+		if (vma_is_special_mapping(vma, vdso_info.dm))
 			zap_page_range(vma, vma->vm_start, size);
+#ifdef CONFIG_COMPAT
+		if (vma_is_special_mapping(vma, compat_vdso_info.dm))
+			zap_page_range(vma, vma->vm_start, size);
+#endif
 	}

 	mmap_read_unlock(mm);
@@ -264,7 +269,6 @@ static int __setup_additional_pages(struct mm_struct *mm,

 	vdso_base += VVAR_SIZE;
 	mm->context.vdso = (void *)vdso_base;
-	mm->context.vdso_info = (void *)vdso_info;

 	ret =
 	   _install_special_mapping(mm, vdso_base, vdso_text_len,

>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation")
> ---
>
> since v1:
>  - add "Fixes" tag
>  - fix build error when CONFIG_COMPAT is enabled.
>
>  arch/riscv/include/asm/mmu.h |   1 -
>  arch/riscv/kernel/vdso.c     | 178 +++++++++++++++++++----------------
>  2 files changed, 95 insertions(+), 84 deletions(-)
>
> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> index cedcf8ea3c76..0099dc116168 100644
> --- a/arch/riscv/include/asm/mmu.h
> +++ b/arch/riscv/include/asm/mmu.h
> @@ -16,7 +16,6 @@ typedef struct {
>  	atomic_long_t id;
>  #endif
>  	void *vdso;
> -	void *vdso_info;
>  #ifdef CONFIG_SMP
>  	/* A local icache flush is needed before user execution can resume. */
>  	cpumask_t icache_stale_mask;
> diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
> index 69b05b6c181b..8ca3b821e1b5 100644
> --- a/arch/riscv/kernel/vdso.c
> +++ b/arch/riscv/kernel/vdso.c
> @@ -27,6 +27,11 @@ extern char vdso_start[], vdso_end[];
>  extern char compat_vdso_start[], compat_vdso_end[];
>  #endif
>
> +enum vdso_abi {
> +	VDSO_ABI_RV64,
> +	VDSO_ABI_RV32,
> +};
> +
>  enum vvar_pages {
>  	VVAR_DATA_PAGE_OFFSET,
>  	VVAR_TIMENS_PAGE_OFFSET,
> @@ -68,67 +73,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
>  	return 0;
>  }
>
> -static void __init __vdso_init(struct __vdso_info *vdso_info)
> -{
> -	unsigned int i;
> -	struct page **vdso_pagelist;
> -	unsigned long pfn;
> -
> -	if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
> -		panic("vDSO is not a valid ELF object!\n");
> -
> -	vdso_info->vdso_pages = (
> -		vdso_info->vdso_code_end -
> -		vdso_info->vdso_code_start) >>
> -		PAGE_SHIFT;
> -
> -	vdso_pagelist = kcalloc(vdso_info->vdso_pages,
> -				sizeof(struct page *),
> -				GFP_KERNEL);
> -	if (vdso_pagelist == NULL)
> -		panic("vDSO kcalloc failed!\n");
> -
> -	/* Grab the vDSO code pages. */
> -	pfn = sym_to_pfn(vdso_info->vdso_code_start);
> -
> -	for (i = 0; i < vdso_info->vdso_pages; i++)
> -		vdso_pagelist[i] = pfn_to_page(pfn + i);
> -
> -	vdso_info->cm->pages = vdso_pagelist;
> -}
> -
>  #ifdef CONFIG_TIME_NS
> -struct vdso_data *arch_get_vdso_data(void *vvar_page)
> -{
> -	return (struct vdso_data *)(vvar_page);
> -}
> -
> -/*
> - * The vvar mapping contains data for a specific time namespace, so when a task
> - * changes namespace we must unmap its vvar data for the old namespace.
> - * Subsequent faults will map in data for the new namespace.
> - *
> - * For more details see timens_setup_vdso_data().
> - */
> -int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> -{
> -	struct mm_struct *mm = task->mm;
> -	struct vm_area_struct *vma;
> -	struct __vdso_info *vdso_info = mm->context.vdso_info;
> -
> -	mmap_read_lock(mm);
> -
> -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> -		unsigned long size = vma->vm_end - vma->vm_start;
> -
> -		if (vma_is_special_mapping(vma, vdso_info->dm))
> -			zap_page_range(vma, vma->vm_start, size);
> -	}
> -
> -	mmap_read_unlock(mm);
> -	return 0;
> -}
> -
>  static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
>  {
>  	if (likely(vma->vm_mm == current->mm))
> @@ -197,13 +142,6 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
>  	},
>  };
>
> -static struct __vdso_info vdso_info __ro_after_init = {
> -	.name = "vdso",
> -	.vdso_code_start = vdso_start,
> -	.vdso_code_end = vdso_end,
> -	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> -	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> -};
>
>  #ifdef CONFIG_COMPAT
>  static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
> @@ -216,21 +154,97 @@ static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
>  		.mremap = vdso_mremap,
>  	},
>  };
> +#endif
>
> -static struct __vdso_info compat_vdso_info __ro_after_init = {
> -	.name = "compat_vdso",
> -	.vdso_code_start = compat_vdso_start,
> -	.vdso_code_end = compat_vdso_end,
> -	.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> -	.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> +static struct __vdso_info vdso_info[] __ro_after_init = {
> +	[VDSO_ABI_RV64] = {
> +		.name = "vdso",
> +		.vdso_code_start = vdso_start,
> +		.vdso_code_end = vdso_end,
> +		.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> +		.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> +	},
> +#ifdef CONFIG_COMPAT
> +	[VDSO_ABI_RV32] = {
> +		.name = "compat_vdso",
> +		.vdso_code_start = compat_vdso_start,
> +		.vdso_code_end = compat_vdso_end,
> +		.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> +		.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> +	},
> +#endif
>  };
> +
> +static void __init __vdso_init(enum vdso_abi abi)
> +{
> +	unsigned int i;
> +	struct page **vdso_pagelist;
> +	unsigned long pfn;
> +
> +	if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4))
> +		panic("vDSO is not a valid ELF object!\n");
> +
> +	vdso_info[abi].vdso_pages = (
> +		vdso_info[abi].vdso_code_end -
> +		vdso_info[abi].vdso_code_start) >>
> +		PAGE_SHIFT;
> +
> +	vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages,
> +				sizeof(struct page *),
> +				GFP_KERNEL);
> +	if (vdso_pagelist == NULL)
> +		panic("vDSO kcalloc failed!\n");
> +
> +	/* Grab the vDSO code pages. */
> +	pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
> +
> +	for (i = 0; i < vdso_info[abi].vdso_pages; i++)
> +		vdso_pagelist[i] = pfn_to_page(pfn + i);
> +
> +	vdso_info[abi].cm->pages = vdso_pagelist;
> +}
> +
> +#ifdef CONFIG_TIME_NS
> +struct vdso_data *arch_get_vdso_data(void *vvar_page)
> +{
> +	return (struct vdso_data *)(vvar_page);
> +}
> +
> +/*
> + * The vvar mapping contains data for a specific time namespace, so when a task
> + * changes namespace we must unmap its vvar data for the old namespace.
> + * Subsequent faults will map in data for the new namespace.
> + *
> + * For more details see timens_setup_vdso_data().
> + */
> +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> +{
> +	struct mm_struct *mm = task->mm;
> +	struct vm_area_struct *vma;
> +
> +	mmap_read_lock(mm);
> +
> +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +		unsigned long size = vma->vm_end - vma->vm_start;
> +
> +		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV64].dm))
> +			zap_page_range(vma, vma->vm_start, size);
> +#ifdef CONFIG_COMPAT
> +		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV32].dm))
> +			zap_page_range(vma, vma->vm_start, size);
> +#endif
> +	}
> +
> +	mmap_read_unlock(mm);
> +	return 0;
> +}
>  #endif
>
>  static int __init vdso_init(void)
>  {
> -	__vdso_init(&vdso_info);
> +	__vdso_init(VDSO_ABI_RV64);
>  #ifdef CONFIG_COMPAT
> -	__vdso_init(&compat_vdso_info);
> +	__vdso_init(VDSO_ABI_RV32);
>  #endif
>
>  	return 0;
> @@ -240,14 +254,14 @@ arch_initcall(vdso_init);
>  static int __setup_additional_pages(struct mm_struct *mm,
>  				    struct linux_binprm *bprm,
>  				    int uses_interp,
> -				    struct __vdso_info *vdso_info)
> +				    enum vdso_abi abi)
>  {
>  	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
>  	void *ret;
>
>  	BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
>
> -	vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
> +	vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
>  	/* Be sure to map the data page */
>  	vdso_mapping_len = vdso_text_len + VVAR_SIZE;
>
> @@ -258,18 +272,17 @@ static int __setup_additional_pages(struct mm_struct *mm,
>  	}
>
>  	ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
> -		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
> +		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info[abi].dm);
>  	if (IS_ERR(ret))
>  		goto up_fail;
>
>  	vdso_base += VVAR_SIZE;
>  	mm->context.vdso = (void *)vdso_base;
> -	mm->context.vdso_info = (void *)vdso_info;
>
>  	ret =
>  	   _install_special_mapping(mm, vdso_base, vdso_text_len,
>  		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
> -		vdso_info->cm);
> +		vdso_info[abi].cm);
>
>  	if (IS_ERR(ret))
>  		goto up_fail;
> @@ -291,8 +304,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
>  	if (mmap_write_lock_killable(mm))
>  		return -EINTR;
>
> -	ret = __setup_additional_pages(mm, bprm, uses_interp,
> -							&compat_vdso_info);
> +	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV32);
>  	mmap_write_unlock(mm);
>
>  	return ret;
> @@ -307,7 +319,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
>  	if (mmap_write_lock_killable(mm))
>  		return -EINTR;
>
> -	ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
> +	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV64);
>  	mmap_write_unlock(mm);
>
>  	return ret;

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Re: [PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork

[Jisheng Zhang]

On Thu, Sep 15, 2022 at 11:02:19AM -0700, Palmer Dabbelt wrote:
> On Thu, 08 Sep 2022 08:04:21 PDT (-0700), jszhang@kernel.org wrote:
> > Testing tools/testing/selftests/timens/vfork_exec.c got below
> > kernel log:
> > 
> > [    6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020
> > [    6.842255] Oops [#1]
> > [    6.842871] Modules linked in:
> > [    6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8
> > [    6.845861] Hardware name: riscv-virtio,qemu (DT)
> > [    6.848009] epc : vdso_join_timens+0xd2/0x110
> > [    6.850097]  ra : vdso_join_timens+0xd2/0x110
> > [    6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0
> > [    6.852562]  gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030
> > [    6.853852]  t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40
> > [    6.854984]  s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c
> > [    6.856221]  a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000
> > [    6.858114]  a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
> > [    6.859484]  s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000
> > [    6.860751]  s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38
> > [    6.862029]  s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e
> > [    6.863304]  s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f
> > [    6.864565]  t5 : ffffffff80d11130 t6 : ff6000000181fa00
> > [    6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d
> > [    6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a
> > [    6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4
> > [    6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0
> > [    6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214
> > [    6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4
> > [    6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee
> > [    6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48
> > [    6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2
> > [    6.877484] ---[ end trace 0000000000000000 ]---
> > 
> > This is because the mm->context.vdso_info is NULL in vfork case. From
> > another side, mm->context.vdso_info either points to vdso info
> > for RV64 or vdso info for compat, there's no need to bloat riscv's
> > mm_context_t, we can handle the difference when setup the additional
> > page for vdso.
> 
> Makes sense, but I think there's a lot more diff here than we need in order

The reason of "a lot more diff" is moving the code to avoid forward declaration.
If you prefer smaller fix, I can provide a simpler one w/ forware
declaration. And provide a new clean up patch for next window, what do you
think?

Thanks
> to just fix the bug.  Does something like the following still fix it?  Also
> at kernel.org/palmer/vdso-fix-v3 .  Maybe it's a bit pedantic , but this
> late in the cycle with everyone traveling I'd prefer to keep the fixes
> smaller when possible.
> 
> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> index cedcf8ea3c76..0099dc116168 100644
> --- a/arch/riscv/include/asm/mmu.h
> +++ b/arch/riscv/include/asm/mmu.h
> @@ -16,7 +16,6 @@ typedef struct {
> 	atomic_long_t id;
> #endif
> 	void *vdso;
> -	void *vdso_info;
> #ifdef CONFIG_SMP
> 	/* A local icache flush is needed before user execution can resume. */
> 	cpumask_t icache_stale_mask;
> diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
> index 69b05b6c181b..58b8d73a4b1f 100644
> --- a/arch/riscv/kernel/vdso.c
> +++ b/arch/riscv/kernel/vdso.c
> @@ -23,8 +23,10 @@ struct vdso_data {
> #endif
> 
> extern char vdso_start[], vdso_end[];
> +static struct __vdso_info vdso_info;
> #ifdef CONFIG_COMPAT
> extern char compat_vdso_start[], compat_vdso_end[];
> +static struct __vdso_info compat_vdso_info;
> #endif
> 
> enum vvar_pages {
> @@ -114,15 +116,18 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> {
> 	struct mm_struct *mm = task->mm;
> 	struct vm_area_struct *vma;
> -	struct __vdso_info *vdso_info = mm->context.vdso_info;
> 
> 	mmap_read_lock(mm);
> 
> 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> 		unsigned long size = vma->vm_end - vma->vm_start;
> 
> -		if (vma_is_special_mapping(vma, vdso_info->dm))
> +		if (vma_is_special_mapping(vma, vdso_info.dm))
> 			zap_page_range(vma, vma->vm_start, size);
> +#ifdef CONFIG_COMPAT
> +		if (vma_is_special_mapping(vma, compat_vdso_info.dm))
> +			zap_page_range(vma, vma->vm_start, size);
> +#endif
> 	}
> 
> 	mmap_read_unlock(mm);
> @@ -264,7 +269,6 @@ static int __setup_additional_pages(struct mm_struct *mm,
> 
> 	vdso_base += VVAR_SIZE;
> 	mm->context.vdso = (void *)vdso_base;
> -	mm->context.vdso_info = (void *)vdso_info;
> 
> 	ret =
> 	   _install_special_mapping(mm, vdso_base, vdso_text_len,
> 
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation")
> > ---
> > 
> > since v1:
> >  - add "Fixes" tag
> >  - fix build error when CONFIG_COMPAT is enabled.
> > 
> >  arch/riscv/include/asm/mmu.h |   1 -
> >  arch/riscv/kernel/vdso.c     | 178 +++++++++++++++++++----------------
> >  2 files changed, 95 insertions(+), 84 deletions(-)
> > 
> > diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> > index cedcf8ea3c76..0099dc116168 100644
> > --- a/arch/riscv/include/asm/mmu.h
> > +++ b/arch/riscv/include/asm/mmu.h
> > @@ -16,7 +16,6 @@ typedef struct {
> >  	atomic_long_t id;
> >  #endif
> >  	void *vdso;
> > -	void *vdso_info;
> >  #ifdef CONFIG_SMP
> >  	/* A local icache flush is needed before user execution can resume. */
> >  	cpumask_t icache_stale_mask;
> > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
> > index 69b05b6c181b..8ca3b821e1b5 100644
> > --- a/arch/riscv/kernel/vdso.c
> > +++ b/arch/riscv/kernel/vdso.c
> > @@ -27,6 +27,11 @@ extern char vdso_start[], vdso_end[];
> >  extern char compat_vdso_start[], compat_vdso_end[];
> >  #endif
> > 
> > +enum vdso_abi {
> > +	VDSO_ABI_RV64,
> > +	VDSO_ABI_RV32,
> > +};
> > +
> >  enum vvar_pages {
> >  	VVAR_DATA_PAGE_OFFSET,
> >  	VVAR_TIMENS_PAGE_OFFSET,
> > @@ -68,67 +73,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
> >  	return 0;
> >  }
> > 
> > -static void __init __vdso_init(struct __vdso_info *vdso_info)
> > -{
> > -	unsigned int i;
> > -	struct page **vdso_pagelist;
> > -	unsigned long pfn;
> > -
> > -	if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
> > -		panic("vDSO is not a valid ELF object!\n");
> > -
> > -	vdso_info->vdso_pages = (
> > -		vdso_info->vdso_code_end -
> > -		vdso_info->vdso_code_start) >>
> > -		PAGE_SHIFT;
> > -
> > -	vdso_pagelist = kcalloc(vdso_info->vdso_pages,
> > -				sizeof(struct page *),
> > -				GFP_KERNEL);
> > -	if (vdso_pagelist == NULL)
> > -		panic("vDSO kcalloc failed!\n");
> > -
> > -	/* Grab the vDSO code pages. */
> > -	pfn = sym_to_pfn(vdso_info->vdso_code_start);
> > -
> > -	for (i = 0; i < vdso_info->vdso_pages; i++)
> > -		vdso_pagelist[i] = pfn_to_page(pfn + i);
> > -
> > -	vdso_info->cm->pages = vdso_pagelist;
> > -}
> > -
> >  #ifdef CONFIG_TIME_NS
> > -struct vdso_data *arch_get_vdso_data(void *vvar_page)
> > -{
> > -	return (struct vdso_data *)(vvar_page);
> > -}
> > -
> > -/*
> > - * The vvar mapping contains data for a specific time namespace, so when a task
> > - * changes namespace we must unmap its vvar data for the old namespace.
> > - * Subsequent faults will map in data for the new namespace.
> > - *
> > - * For more details see timens_setup_vdso_data().
> > - */
> > -int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> > -{
> > -	struct mm_struct *mm = task->mm;
> > -	struct vm_area_struct *vma;
> > -	struct __vdso_info *vdso_info = mm->context.vdso_info;
> > -
> > -	mmap_read_lock(mm);
> > -
> > -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> > -		unsigned long size = vma->vm_end - vma->vm_start;
> > -
> > -		if (vma_is_special_mapping(vma, vdso_info->dm))
> > -			zap_page_range(vma, vma->vm_start, size);
> > -	}
> > -
> > -	mmap_read_unlock(mm);
> > -	return 0;
> > -}
> > -
> >  static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
> >  {
> >  	if (likely(vma->vm_mm == current->mm))
> > @@ -197,13 +142,6 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
> >  	},
> >  };
> > 
> > -static struct __vdso_info vdso_info __ro_after_init = {
> > -	.name = "vdso",
> > -	.vdso_code_start = vdso_start,
> > -	.vdso_code_end = vdso_end,
> > -	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> > -	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> > -};
> > 
> >  #ifdef CONFIG_COMPAT
> >  static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
> > @@ -216,21 +154,97 @@ static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
> >  		.mremap = vdso_mremap,
> >  	},
> >  };
> > +#endif
> > 
> > -static struct __vdso_info compat_vdso_info __ro_after_init = {
> > -	.name = "compat_vdso",
> > -	.vdso_code_start = compat_vdso_start,
> > -	.vdso_code_end = compat_vdso_end,
> > -	.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> > -	.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> > +static struct __vdso_info vdso_info[] __ro_after_init = {
> > +	[VDSO_ABI_RV64] = {
> > +		.name = "vdso",
> > +		.vdso_code_start = vdso_start,
> > +		.vdso_code_end = vdso_end,
> > +		.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
> > +		.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
> > +	},
> > +#ifdef CONFIG_COMPAT
> > +	[VDSO_ABI_RV32] = {
> > +		.name = "compat_vdso",
> > +		.vdso_code_start = compat_vdso_start,
> > +		.vdso_code_end = compat_vdso_end,
> > +		.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
> > +		.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
> > +	},
> > +#endif
> >  };
> > +
> > +static void __init __vdso_init(enum vdso_abi abi)
> > +{
> > +	unsigned int i;
> > +	struct page **vdso_pagelist;
> > +	unsigned long pfn;
> > +
> > +	if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4))
> > +		panic("vDSO is not a valid ELF object!\n");
> > +
> > +	vdso_info[abi].vdso_pages = (
> > +		vdso_info[abi].vdso_code_end -
> > +		vdso_info[abi].vdso_code_start) >>
> > +		PAGE_SHIFT;
> > +
> > +	vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages,
> > +				sizeof(struct page *),
> > +				GFP_KERNEL);
> > +	if (vdso_pagelist == NULL)
> > +		panic("vDSO kcalloc failed!\n");
> > +
> > +	/* Grab the vDSO code pages. */
> > +	pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
> > +
> > +	for (i = 0; i < vdso_info[abi].vdso_pages; i++)
> > +		vdso_pagelist[i] = pfn_to_page(pfn + i);
> > +
> > +	vdso_info[abi].cm->pages = vdso_pagelist;
> > +}
> > +
> > +#ifdef CONFIG_TIME_NS
> > +struct vdso_data *arch_get_vdso_data(void *vvar_page)
> > +{
> > +	return (struct vdso_data *)(vvar_page);
> > +}
> > +
> > +/*
> > + * The vvar mapping contains data for a specific time namespace, so when a task
> > + * changes namespace we must unmap its vvar data for the old namespace.
> > + * Subsequent faults will map in data for the new namespace.
> > + *
> > + * For more details see timens_setup_vdso_data().
> > + */
> > +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
> > +{
> > +	struct mm_struct *mm = task->mm;
> > +	struct vm_area_struct *vma;
> > +
> > +	mmap_read_lock(mm);
> > +
> > +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> > +		unsigned long size = vma->vm_end - vma->vm_start;
> > +
> > +		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV64].dm))
> > +			zap_page_range(vma, vma->vm_start, size);
> > +#ifdef CONFIG_COMPAT
> > +		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV32].dm))
> > +			zap_page_range(vma, vma->vm_start, size);
> > +#endif
> > +	}
> > +
> > +	mmap_read_unlock(mm);
> > +	return 0;
> > +}
> >  #endif
> > 
> >  static int __init vdso_init(void)
> >  {
> > -	__vdso_init(&vdso_info);
> > +	__vdso_init(VDSO_ABI_RV64);
> >  #ifdef CONFIG_COMPAT
> > -	__vdso_init(&compat_vdso_info);
> > +	__vdso_init(VDSO_ABI_RV32);
> >  #endif
> > 
> >  	return 0;
> > @@ -240,14 +254,14 @@ arch_initcall(vdso_init);
> >  static int __setup_additional_pages(struct mm_struct *mm,
> >  				    struct linux_binprm *bprm,
> >  				    int uses_interp,
> > -				    struct __vdso_info *vdso_info)
> > +				    enum vdso_abi abi)
> >  {
> >  	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
> >  	void *ret;
> > 
> >  	BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
> > 
> > -	vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
> > +	vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
> >  	/* Be sure to map the data page */
> >  	vdso_mapping_len = vdso_text_len + VVAR_SIZE;
> > 
> > @@ -258,18 +272,17 @@ static int __setup_additional_pages(struct mm_struct *mm,
> >  	}
> > 
> >  	ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
> > -		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
> > +		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info[abi].dm);
> >  	if (IS_ERR(ret))
> >  		goto up_fail;
> > 
> >  	vdso_base += VVAR_SIZE;
> >  	mm->context.vdso = (void *)vdso_base;
> > -	mm->context.vdso_info = (void *)vdso_info;
> > 
> >  	ret =
> >  	   _install_special_mapping(mm, vdso_base, vdso_text_len,
> >  		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
> > -		vdso_info->cm);
> > +		vdso_info[abi].cm);
> > 
> >  	if (IS_ERR(ret))
> >  		goto up_fail;
> > @@ -291,8 +304,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
> >  	if (mmap_write_lock_killable(mm))
> >  		return -EINTR;
> > 
> > -	ret = __setup_additional_pages(mm, bprm, uses_interp,
> > -							&compat_vdso_info);
> > +	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV32);
> >  	mmap_write_unlock(mm);
> > 
> >  	return ret;
> > @@ -307,7 +319,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
> >  	if (mmap_write_lock_killable(mm))
> >  		return -EINTR;
> > 
> > -	ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
> > +	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV64);
> >  	mmap_write_unlock(mm);
> > 
> >  	return ret;

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Re: [PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork

[Palmer Dabbelt]

On Thu, 22 Sep 2022 05:07:44 PDT (-0700), jszhang@kernel.org wrote:
> On Thu, Sep 15, 2022 at 11:02:19AM -0700, Palmer Dabbelt wrote:
>> On Thu, 08 Sep 2022 08:04:21 PDT (-0700), jszhang@kernel.org wrote:
>> > Testing tools/testing/selftests/timens/vfork_exec.c got below
>> > kernel log:
>> >
>> > [    6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020
>> > [    6.842255] Oops [#1]
>> > [    6.842871] Modules linked in:
>> > [    6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8
>> > [    6.845861] Hardware name: riscv-virtio,qemu (DT)
>> > [    6.848009] epc : vdso_join_timens+0xd2/0x110
>> > [    6.850097]  ra : vdso_join_timens+0xd2/0x110
>> > [    6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0
>> > [    6.852562]  gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030
>> > [    6.853852]  t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40
>> > [    6.854984]  s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c
>> > [    6.856221]  a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000
>> > [    6.858114]  a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038
>> > [    6.859484]  s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000
>> > [    6.860751]  s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38
>> > [    6.862029]  s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e
>> > [    6.863304]  s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f
>> > [    6.864565]  t5 : ffffffff80d11130 t6 : ff6000000181fa00
>> > [    6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d
>> > [    6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a
>> > [    6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4
>> > [    6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0
>> > [    6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214
>> > [    6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4
>> > [    6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee
>> > [    6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48
>> > [    6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2
>> > [    6.877484] ---[ end trace 0000000000000000 ]---
>> >
>> > This is because the mm->context.vdso_info is NULL in vfork case. From
>> > another side, mm->context.vdso_info either points to vdso info
>> > for RV64 or vdso info for compat, there's no need to bloat riscv's
>> > mm_context_t, we can handle the difference when setup the additional
>> > page for vdso.
>>
>> Makes sense, but I think there's a lot more diff here than we need in order
>
> The reason of "a lot more diff" is moving the code to avoid forward declaration.
> If you prefer smaller fix, I can provide a simpler one w/ forware
> declaration. And provide a new clean up patch for next window, what do you
> think?

Works for me.  If you put the two back-to-back on 6.0-rc1 then I can 
avoid the merge conflict.  Thanks!

>
> Thanks
>> to just fix the bug.  Does something like the following still fix it?  Also
>> at kernel.org/palmer/vdso-fix-v3 .  Maybe it's a bit pedantic , but this
>> late in the cycle with everyone traveling I'd prefer to keep the fixes
>> smaller when possible.
>>
>> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
>> index cedcf8ea3c76..0099dc116168 100644
>> --- a/arch/riscv/include/asm/mmu.h
>> +++ b/arch/riscv/include/asm/mmu.h
>> @@ -16,7 +16,6 @@ typedef struct {
>> 	atomic_long_t id;
>> #endif
>> 	void *vdso;
>> -	void *vdso_info;
>> #ifdef CONFIG_SMP
>> 	/* A local icache flush is needed before user execution can resume. */
>> 	cpumask_t icache_stale_mask;
>> diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
>> index 69b05b6c181b..58b8d73a4b1f 100644
>> --- a/arch/riscv/kernel/vdso.c
>> +++ b/arch/riscv/kernel/vdso.c
>> @@ -23,8 +23,10 @@ struct vdso_data {
>> #endif
>>
>> extern char vdso_start[], vdso_end[];
>> +static struct __vdso_info vdso_info;
>> #ifdef CONFIG_COMPAT
>> extern char compat_vdso_start[], compat_vdso_end[];
>> +static struct __vdso_info compat_vdso_info;
>> #endif
>>
>> enum vvar_pages {
>> @@ -114,15 +116,18 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
>> {
>> 	struct mm_struct *mm = task->mm;
>> 	struct vm_area_struct *vma;
>> -	struct __vdso_info *vdso_info = mm->context.vdso_info;
>>
>> 	mmap_read_lock(mm);
>>
>> 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> 		unsigned long size = vma->vm_end - vma->vm_start;
>>
>> -		if (vma_is_special_mapping(vma, vdso_info->dm))
>> +		if (vma_is_special_mapping(vma, vdso_info.dm))
>> 			zap_page_range(vma, vma->vm_start, size);
>> +#ifdef CONFIG_COMPAT
>> +		if (vma_is_special_mapping(vma, compat_vdso_info.dm))
>> +			zap_page_range(vma, vma->vm_start, size);
>> +#endif
>> 	}
>>
>> 	mmap_read_unlock(mm);
>> @@ -264,7 +269,6 @@ static int __setup_additional_pages(struct mm_struct *mm,
>>
>> 	vdso_base += VVAR_SIZE;
>> 	mm->context.vdso = (void *)vdso_base;
>> -	mm->context.vdso_info = (void *)vdso_info;
>>
>> 	ret =
>> 	   _install_special_mapping(mm, vdso_base, vdso_text_len,
>>
>> >
>> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
>> > Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation")
>> > ---
>> >
>> > since v1:
>> >  - add "Fixes" tag
>> >  - fix build error when CONFIG_COMPAT is enabled.
>> >
>> >  arch/riscv/include/asm/mmu.h |   1 -
>> >  arch/riscv/kernel/vdso.c     | 178 +++++++++++++++++++----------------
>> >  2 files changed, 95 insertions(+), 84 deletions(-)
>> >
>> > diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
>> > index cedcf8ea3c76..0099dc116168 100644
>> > --- a/arch/riscv/include/asm/mmu.h
>> > +++ b/arch/riscv/include/asm/mmu.h
>> > @@ -16,7 +16,6 @@ typedef struct {
>> >  	atomic_long_t id;
>> >  #endif
>> >  	void *vdso;
>> > -	void *vdso_info;
>> >  #ifdef CONFIG_SMP
>> >  	/* A local icache flush is needed before user execution can resume. */
>> >  	cpumask_t icache_stale_mask;
>> > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
>> > index 69b05b6c181b..8ca3b821e1b5 100644
>> > --- a/arch/riscv/kernel/vdso.c
>> > +++ b/arch/riscv/kernel/vdso.c
>> > @@ -27,6 +27,11 @@ extern char vdso_start[], vdso_end[];
>> >  extern char compat_vdso_start[], compat_vdso_end[];
>> >  #endif
>> >
>> > +enum vdso_abi {
>> > +	VDSO_ABI_RV64,
>> > +	VDSO_ABI_RV32,
>> > +};
>> > +
>> >  enum vvar_pages {
>> >  	VVAR_DATA_PAGE_OFFSET,
>> >  	VVAR_TIMENS_PAGE_OFFSET,
>> > @@ -68,67 +73,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
>> >  	return 0;
>> >  }
>> >
>> > -static void __init __vdso_init(struct __vdso_info *vdso_info)
>> > -{
>> > -	unsigned int i;
>> > -	struct page **vdso_pagelist;
>> > -	unsigned long pfn;
>> > -
>> > -	if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
>> > -		panic("vDSO is not a valid ELF object!\n");
>> > -
>> > -	vdso_info->vdso_pages = (
>> > -		vdso_info->vdso_code_end -
>> > -		vdso_info->vdso_code_start) >>
>> > -		PAGE_SHIFT;
>> > -
>> > -	vdso_pagelist = kcalloc(vdso_info->vdso_pages,
>> > -				sizeof(struct page *),
>> > -				GFP_KERNEL);
>> > -	if (vdso_pagelist == NULL)
>> > -		panic("vDSO kcalloc failed!\n");
>> > -
>> > -	/* Grab the vDSO code pages. */
>> > -	pfn = sym_to_pfn(vdso_info->vdso_code_start);
>> > -
>> > -	for (i = 0; i < vdso_info->vdso_pages; i++)
>> > -		vdso_pagelist[i] = pfn_to_page(pfn + i);
>> > -
>> > -	vdso_info->cm->pages = vdso_pagelist;
>> > -}
>> > -
>> >  #ifdef CONFIG_TIME_NS
>> > -struct vdso_data *arch_get_vdso_data(void *vvar_page)
>> > -{
>> > -	return (struct vdso_data *)(vvar_page);
>> > -}
>> > -
>> > -/*
>> > - * The vvar mapping contains data for a specific time namespace, so when a task
>> > - * changes namespace we must unmap its vvar data for the old namespace.
>> > - * Subsequent faults will map in data for the new namespace.
>> > - *
>> > - * For more details see timens_setup_vdso_data().
>> > - */
>> > -int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
>> > -{
>> > -	struct mm_struct *mm = task->mm;
>> > -	struct vm_area_struct *vma;
>> > -	struct __vdso_info *vdso_info = mm->context.vdso_info;
>> > -
>> > -	mmap_read_lock(mm);
>> > -
>> > -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> > -		unsigned long size = vma->vm_end - vma->vm_start;
>> > -
>> > -		if (vma_is_special_mapping(vma, vdso_info->dm))
>> > -			zap_page_range(vma, vma->vm_start, size);
>> > -	}
>> > -
>> > -	mmap_read_unlock(mm);
>> > -	return 0;
>> > -}
>> > -
>> >  static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
>> >  {
>> >  	if (likely(vma->vm_mm == current->mm))
>> > @@ -197,13 +142,6 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
>> >  	},
>> >  };
>> >
>> > -static struct __vdso_info vdso_info __ro_after_init = {
>> > -	.name = "vdso",
>> > -	.vdso_code_start = vdso_start,
>> > -	.vdso_code_end = vdso_end,
>> > -	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
>> > -	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
>> > -};
>> >
>> >  #ifdef CONFIG_COMPAT
>> >  static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
>> > @@ -216,21 +154,97 @@ static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = {
>> >  		.mremap = vdso_mremap,
>> >  	},
>> >  };
>> > +#endif
>> >
>> > -static struct __vdso_info compat_vdso_info __ro_after_init = {
>> > -	.name = "compat_vdso",
>> > -	.vdso_code_start = compat_vdso_start,
>> > -	.vdso_code_end = compat_vdso_end,
>> > -	.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
>> > -	.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
>> > +static struct __vdso_info vdso_info[] __ro_after_init = {
>> > +	[VDSO_ABI_RV64] = {
>> > +		.name = "vdso",
>> > +		.vdso_code_start = vdso_start,
>> > +		.vdso_code_end = vdso_end,
>> > +		.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
>> > +		.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
>> > +	},
>> > +#ifdef CONFIG_COMPAT
>> > +	[VDSO_ABI_RV32] = {
>> > +		.name = "compat_vdso",
>> > +		.vdso_code_start = compat_vdso_start,
>> > +		.vdso_code_end = compat_vdso_end,
>> > +		.dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR],
>> > +		.cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO],
>> > +	},
>> > +#endif
>> >  };
>> > +
>> > +static void __init __vdso_init(enum vdso_abi abi)
>> > +{
>> > +	unsigned int i;
>> > +	struct page **vdso_pagelist;
>> > +	unsigned long pfn;
>> > +
>> > +	if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4))
>> > +		panic("vDSO is not a valid ELF object!\n");
>> > +
>> > +	vdso_info[abi].vdso_pages = (
>> > +		vdso_info[abi].vdso_code_end -
>> > +		vdso_info[abi].vdso_code_start) >>
>> > +		PAGE_SHIFT;
>> > +
>> > +	vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages,
>> > +				sizeof(struct page *),
>> > +				GFP_KERNEL);
>> > +	if (vdso_pagelist == NULL)
>> > +		panic("vDSO kcalloc failed!\n");
>> > +
>> > +	/* Grab the vDSO code pages. */
>> > +	pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
>> > +
>> > +	for (i = 0; i < vdso_info[abi].vdso_pages; i++)
>> > +		vdso_pagelist[i] = pfn_to_page(pfn + i);
>> > +
>> > +	vdso_info[abi].cm->pages = vdso_pagelist;
>> > +}
>> > +
>> > +#ifdef CONFIG_TIME_NS
>> > +struct vdso_data *arch_get_vdso_data(void *vvar_page)
>> > +{
>> > +	return (struct vdso_data *)(vvar_page);
>> > +}
>> > +
>> > +/*
>> > + * The vvar mapping contains data for a specific time namespace, so when a task
>> > + * changes namespace we must unmap its vvar data for the old namespace.
>> > + * Subsequent faults will map in data for the new namespace.
>> > + *
>> > + * For more details see timens_setup_vdso_data().
>> > + */
>> > +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
>> > +{
>> > +	struct mm_struct *mm = task->mm;
>> > +	struct vm_area_struct *vma;
>> > +
>> > +	mmap_read_lock(mm);
>> > +
>> > +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> > +		unsigned long size = vma->vm_end - vma->vm_start;
>> > +
>> > +		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV64].dm))
>> > +			zap_page_range(vma, vma->vm_start, size);
>> > +#ifdef CONFIG_COMPAT
>> > +		if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV32].dm))
>> > +			zap_page_range(vma, vma->vm_start, size);
>> > +#endif
>> > +	}
>> > +
>> > +	mmap_read_unlock(mm);
>> > +	return 0;
>> > +}
>> >  #endif
>> >
>> >  static int __init vdso_init(void)
>> >  {
>> > -	__vdso_init(&vdso_info);
>> > +	__vdso_init(VDSO_ABI_RV64);
>> >  #ifdef CONFIG_COMPAT
>> > -	__vdso_init(&compat_vdso_info);
>> > +	__vdso_init(VDSO_ABI_RV32);
>> >  #endif
>> >
>> >  	return 0;
>> > @@ -240,14 +254,14 @@ arch_initcall(vdso_init);
>> >  static int __setup_additional_pages(struct mm_struct *mm,
>> >  				    struct linux_binprm *bprm,
>> >  				    int uses_interp,
>> > -				    struct __vdso_info *vdso_info)
>> > +				    enum vdso_abi abi)
>> >  {
>> >  	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
>> >  	void *ret;
>> >
>> >  	BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
>> >
>> > -	vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
>> > +	vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
>> >  	/* Be sure to map the data page */
>> >  	vdso_mapping_len = vdso_text_len + VVAR_SIZE;
>> >
>> > @@ -258,18 +272,17 @@ static int __setup_additional_pages(struct mm_struct *mm,
>> >  	}
>> >
>> >  	ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
>> > -		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
>> > +		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info[abi].dm);
>> >  	if (IS_ERR(ret))
>> >  		goto up_fail;
>> >
>> >  	vdso_base += VVAR_SIZE;
>> >  	mm->context.vdso = (void *)vdso_base;
>> > -	mm->context.vdso_info = (void *)vdso_info;
>> >
>> >  	ret =
>> >  	   _install_special_mapping(mm, vdso_base, vdso_text_len,
>> >  		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
>> > -		vdso_info->cm);
>> > +		vdso_info[abi].cm);
>> >
>> >  	if (IS_ERR(ret))
>> >  		goto up_fail;
>> > @@ -291,8 +304,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
>> >  	if (mmap_write_lock_killable(mm))
>> >  		return -EINTR;
>> >
>> > -	ret = __setup_additional_pages(mm, bprm, uses_interp,
>> > -							&compat_vdso_info);
>> > +	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV32);
>> >  	mmap_write_unlock(mm);
>> >
>> >  	return ret;
>> > @@ -307,7 +319,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
>> >  	if (mmap_write_lock_killable(mm))
>> >  		return -EINTR;
>> >
>> > -	ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
>> > +	ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV64);
>> >  	mmap_write_unlock(mm);
>> >
>> >  	return ret;

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