Messages in this thread Patch in this message | | | From | Jisheng Zhang <> | Subject | [PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork | Date | Thu, 8 Sep 2022 23:04:21 +0800 |
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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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