[PATCH] vdso: fix NULL deference in vdso_join_timens() when vfork
From: Jisheng Zhang
Date: Wed Sep 07 2022 - 13:07:55 EST
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 due to 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@xxxxxxxxxx>
---
arch/riscv/include/asm/mmu.h | 1 -
arch/riscv/kernel/vdso.c | 177 +++++++++++++++++++----------------
2 files changed, 94 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..0cac2b9fa908 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))
@@ -197,12 +142,23 @@ 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],
+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
};
#ifdef CONFIG_COMPAT
@@ -216,21 +172,78 @@ 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 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 +253,14 @@ 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 +271,17 @@ 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 +303,7 @@ 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 +318,7 @@ 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